NONIUS CAD4/MACH3 User manual

Data collection features

The CAD4 data collection routine provides a large number of features which enable the user to configure the data collection process to his needs. Detailed information is presented in the remainder of this section.

The indices of the reflections to be measured may be derived in three ways

• by a zigzag routine which minimizes goniometer motion
• from a previously prepared list, or
• individually, specified on-line by the operator through the keybord.

The azimuthal angle of the reflection to be measured may be determined in several ways

• it may be specified explicitely
• be set to zero (bisecting position)
• be chosen by the programs for minimum absorption, or
• be chosen by the program in case of anisotropic splitting of the profiles.

Intensity measurement begins with a pre-scan using a user specified speed. Information thus obtained determines whether the reflection is observed or whether a slower final scan should be done. Pre-scan data is used to determine the final scan speed and thus the quality of the final scan data. The actual measurement of the reflection provides for: variable Omega scan angle, Omega-Theta scans from pure omega scans in ratios up to Omega/2Theta, stationary "Peak Top" measurements, variable detector aperture and a repeated scan equality test for verifying proper operation.

Sophisticated intensity and orientation control, using a list of up to 25 reflections, includes the ability to reorient the crystal during data collection and the ability to halt the program if the crystal cannot be recentered properly, as well as the ability to halt if the intensity of a control reflection drops below a specified fraction of its original value.

Data collection may be easily interrupted and restarted. A number of users may share the system without interfering with each others crystal specific information.

The output file contains all the information necessary to reconstruct the entire data collection run, including the optional reflection intensity profile. The output data is well protected against power failure induced system crashes.

Operation of the data collection routine may be monitored from any host terminal and is written to the CAD4 log file. Several parts of the program produce terminal output under control of the switch register.

Data collection control

Introduction

Data collection, initiated by DATCOL, continued by DATCON, is controlled by a group of parameters, most of which are specified by the operator through the DATCIN command. These parameters are described on the following pages under the headings, and in the order, in which they are appear in DATCIN. A mnemonic list and an example are presented in the following section. The parameter group headings are, briefly:

TEXT	Alphanumeric string; title etc.
THLIM	Theta limits.
SCAN	Scan parameters
INT	Intensity measurement parameters.
FLAG	Enables balanced filter unit(if hardware is present, as in older types CAD4), Friedel measurements and non-equal check.
PSI	Azimuth angle setting parameters.
MODE	HKL selecting parameters
ABSENT	Systematic absences to be taken into account
INTCR	Intensity control parameters.
ORIENT	Orientation control parameters
BACKG	Static background measurement parameters.

Wavelength values, attenuation filter factor and the orientation matrix are stored in record 27 of the CRYSTAL file. These values are accessible for read or write with the commands RO, WO, RI, WI, respectively (See pages on CAD4 Control commands).

All information concerning the learnt profile is stored in record 28 of the CRYSTAL file. The currently stored information is available through the command LCL (Chapter IX, section E and Chapter X, section G.5).

Any or all of the 25 reflections in the CRYSTAL file may be used for orientation control and/or intensity control. Reflections are selected by changing the appropriate status codes with the commands LCO and LCI, respectively. (Chapter IX, section E).

As all of the parameters which control data collection are stored in the CRYSTAL file, data collection may be interrupted, the crystal removed and stored and the instrument used for another project. As long as the original CRYSTAL file is not changed, the crystal may be remounted, the orientation matrix refined and data collection continued where it had been left off.

Preparing data collection input

Data collection control parameter examination and modification

Following the command DATCIN, the program prompts 'I, M, O, S, T?' The operator must select the desired function by typing a single character followed by a carriage return.
 

T	TYPE a mnemonic description of the parameters as a guide.
O	OUTPUT the current values of the parameters on the terminal.
I	INPUT all parameters from the operator. The program will request input in groups. The program will print the group heading and the old values. The operator may then type in the new values (or use slashes to retain old values) using the same number of parameters per line and the same number of lines per group that appeared in the output. All parameters are not always needed. In some cases it is necessary to supply values for some parameters to complete an input line. When one group has been given, the program continues with the next group until all necessary values have been entered.
M	MODIFY the parameters in a single group only. The program will print a single quote (') to indicate that it requires the name of a single group. When a name is given, the program prints the group heading, etc., as in INPUT. When the entire group has been given, the program prompts with another quote (') and waits for another name. If no further modification is necessary the operator types Q(uit) to return to the question 'I, M, O, S, T?'. If an improper name is given the program also returns to 'I, M, O, S, T?'
S	SAVE the new values of the parameters in the file. No changes are permanent until they are saved.
Q	If a Q(uit) is typed in response to 'I, M, O, S, T?', the program returns to command mode without saving the new values.

All of the general input rules apply. Of special value is the slash '/'. The slash is used in the event that the original value of a parameter is to be retained. This applies to alphanumeric parameters as well. Consecutive slashes may be used to retain multiple numbers, e.g. //2//(only entry number three is changed; gets value 2).

Example data collection dialogue:

CD0> DATCIN<CR>
I,M,O,S,T? T<CR>
Text = 36 ASCII chars
Thlim  = min max
Scan = Doma Domb Apta Aptb Type
Int = Sigpre Sigma Npipre Maxtime Dumpfl
Flag = Balfil Fridel Non-equal
Psi = Word (is either BISECT or AZIMUT or FLAT orNEEDLE or VECTOR)
N Psist Delpsi V1 V2 V3 (if not BISECT)
Mode = Word (is either ZIGZAG or SEPHKL or FILE)
HMIN HMAX KMIN KMAX LMIN LMAX
HST KST LST
Seq
Absent = Nr
XN YN ZN (Absent if XN and YN and ZN is true)
Intcr  = Reptime Sigmi Fraction
Orient = Repcnt Dev-ang
Backg  = Select (0/1/2) Time (per static meas.) DOMAbg (DOMA for static measurement)

in Absent XN, YN and ZN must be out of the next list
H=0 HN2 HN4 H<0 H>K H>L HN3 AH>AK AH>AL H+KN2 -HKLN3
K=0 KN2 KN4 K<0 K>L K>H KN3 AK>AL AK>AH K+LN2 H-KLN3
L=0 LN2 LN4 L<0 L>H L>K LN3 AL>AH AL>AK L+HN2 HK-LN3
HKLN2 (a blank means no condition)
I,M,O,S,T? O<CR>
TEXT = Crystalname Cu-rad 50kV/26mA date
THLIM = 1.00 69.00
SCAN = 0.60 0.14 2.40 0.30 6
INT = 1.000 0.030 3 60 0
FLAG = 0  0  3
PSI = BISECT 37 0.00 10.00  0.039534  -0.008430  0.125707
MODE = ZIGZAG 0 9 0
9 -20 20 0 0 -20  HKL
ABSENT = 3  H=0 K=0 LN2  H=0 KN2 L=0  HN2 K=0 L=0

INTCR =  3600  0.010 0.100
ORIENT =-120 0.175
BACKG = 0 1.20  0.80
I,M,O,S,T? S<CR>
CD0>

Example of modification of one or more data collection parameters:
CD0> DATCIN<CR>
I,M,O,S,T? M<CR>
' MODE<CR>
ZIGZAG
0  9 0  9 -20 20
0  0 -20
HKL
/<CR>
//////<CR>
//0<CR>
LKH<CR>
' Q<CR>
I,M,O,S,T? S<CR>
CD0>

Data collection control parameters

All inputs to DATCIN are explained adopting the same sequence used in the DATCIN T(ext)-mode and the parameter names which appear have been used.
 

TEXT=
TEXT	A string of 36 alphanumeric characters. This string is for file identification. During input, a / as first character may be used to retain the entire original line. The AT-sign(@) may not be used.
THLIM=
MIN	The minimum Theta boundary for all data collection reflections in degrees.
MAX	The maximum Theta boundary for all data collection reflections in degrees. MAX must be between 0 and THPOS (see GONCON). MIN is limited by and should be less than MAX. These Theta limits dominate the process of selecting the next reflection to be collected. For all modes, ZIGZAG, FILE and SEPHKL, the program checks whether the theta value calculated lies in the range set by MIN and MAX. In ZIGZAG, Theta limits are used in conjunction with a range of indices (see MODE=) to collect a shell. Indices outside the Theta limits will not be collected. The ZIGZAG routine calculates the indices before testing them against the Theta limits. Therefore it is advised to choose the index range approximately in agreement with the boundaries of the shell. The command TH (section D.2 of this Chapter) can be used to obtain the range of indices corresponding to the Theta limits, e.g.,

CD0>
TH<CR>
T1 2?
10 11<CR>
HMAX = 4 KMAX = 4 LMAX = 5 TOTAL = 106.80
CD0>
 

	During data collection THLIM overrules all other conditions. THLIM does not apply to orientation control or intensity control reflections; i.e. orientation and/or intensity control reflections may lay outside the range set by maximum and minimum theta.
SCAN=
DOMA	DOMA and DOMB are used to determine the scan
DOMB	angle of the Omega axis. Omega scan angle = DOMA + DOMB * tan(THETA) (degrees) DOMA depends on the crystal shape and mosaicity and on the divergence of the primary beam (see also Optimum scan parameters and OTPLOT). For a given type of radiation DOMB is a constant used to calculate the widening of the reflection due to split-up in Theta using the formula: THETA(alpha2) = THETA(alpha1) + DOMB * tan[THETA(alpha1)] whereas DOMB = [(LAM2-LAM1)/LAM2]*360/2pi. Type of radiation DOMB(degrees) Ag 0.446 Co 0.124 Cr 0.096 Cu 0.142 Fe 0.116 Mo 0.344 W 1.291 The program will extend the omega scan area (specified by the operator with DOMA and DOMB) at each side with 25% for background determination.
APTA	APTA and APTB are used to determine the horizontal width of
APTB,	the variable aperture at the detector in the same manner as DOMA and DOMB determine the scan angle. APT = APTA + APTB * tan(THETA) (mm) The value of the calculated aperture width is limited by the values stored in GONCON for APTMIN and APTMAX (see Initiating the CAD4). The vertical size of the slit is a goniometer constant and consists of a manually insertable slit, normally 4mm. Spherical crystals of good quality often give better I/sigma(I) ratios when smaller vertical slit sizes than 4 mm are used.
TYPE	The type of scan used for both the prescan and final scan. An integer varying from 0 to 6, it specifies the scan speed of the Theta axis relative to the Omega axis. 0 - no Theta movement; a pure Omega scan 6 - Omega / 2Theta scan n - Theta movement is (n/6)*Omega movement Omega / 2(n/6) Theta scan, i.e., Detector scan angle = (TYPE/3)*Omega scan angle. (degrees) If TYPE is negative, a special stationary 'peak top' measurement is enabled. In this case, the prescan is used to locate the exact peak center and the goniometer is positioned at that location for the entire measurement. No backgrounds are taken; background measurements must be taken separately and processed later. Notes: The actual scan angle is calculated as above, then extended 25% on each side for background measurement. The position of the reflection (center of the scan) is calculated using average wavelength [lambda(alpha1)+lambda(alpha2)]/2 See also optimum parameter selection and the section on the command  OTPLOT which may be used to determine the SCAN parameters.
INT=
SIGPRE	Prescan acceptance parameter. If sigma(I)/I of the prescan is greater than SIGPRE, the reflection is considered unobserved and is flagged weak. If SIGPRE is negative on input, the final intensity is calculated without addition of the PRESCAN data. SIGPRE = 0 is a special case, it forces the final scan to be done. No reflections will be flagged weak. This would be used, for example, when doing "peak top" measurements.
SIGMA	The sigma(I)/I required for the final scan data. Used to calculate the speed of the final scan. If input is equal to 0, the value is reset to 0.03125. If SIGMA is less than 0, the learnt profile as stored in record 28 of the current CRYSTAL file is used.
NPIPRE	Prescan speed parameter. If input equal to or less than 0, the value is reset to 3. Maximum efficiency normally requires NPIPRE be set slow enough for the majority of the observed reflections to be collected using the prescan only, thus minimizing the time spent in final scans. Scan speed = 16.48/NPIPRE (degrees/min)
MAXTIME	Maximum time limit for a final scan in seconds. If input is negative or greater than 600, the value is reset to 600. The time limit overrides all quality requirements.
DUMPFL	Intensity profile output flag. =0, Do not write intensity profile (128 bytes/reflection). =1,5,6, Do write the intensity profile in the output file (640 bytes/reflection). If DUMPFL = 1 the maximum profile value written to the file is 9999. If DUMPFL = 5 each dump value has 5 characters (maximum 99999) and if DUMPFL = 6 a hexadecimal value is written. In case of DUMPFL 5 or 6 there are no record and reflection numbers in the record. Notes on how the scan parameters (INT) correlate: The prescan is done with a fixed speed determined by NPIPRE. The SIGMA(pre) is defined as sigma(I)/I for the prescan. The net intensity of the reflection is INT-2(BGL+BGR). The standard deviation of that is [INT+4(BGL+BGR)]**0.5 , thus: SIGMA(pre) = ([INT+4(BGL+BGR)]**0.5)/[INT-2(BGL+BGR)] If SIGMA(pre) > SIGPRE, the reflection is considered unobserved and is flagged weak in the output. If SIGMA(pre) < SIGMA, no final scan is necessary, the prescan data is of acceptable quality. If a final scan is to be done, a scan speed is now chosen to produce acceptable data. First NPI(max), the maximum allowable scan speed is calculatad. NPI(max) = MAXTIME/3*(Omega scan angle). NPI, the scan speed parameter for the final scan is now calculated, based on the prescan and the required SIGMA. NPI = NPIPRE*[SIGMA(pre)/SIGMA]**2 If the calculated NPI > NPI(max), the final scan will be done using NPI(max). The 96 step intensity profile dump is divided for backgrounds and intensity measurement as follows: BACKGROUND LEFT, BGL dumps 1-16 INTENSITY , INT dumps 17-80 BACKGROUND RIGHT, BGR dumps 81-96
FLAG=
BALFIL	Flag to enable use of the balanced filter unit. =0, do not use balanced filter method =1, use the balanced filter method (only possible on older types CAD4). The reflection is first measured as a normal reflection with filter A. When it is measured successfully, the final scan is repeated with filter B.
FRIDEL	Flag to enable measurement of Friedel pairs =0, do not measure Friedel pairs. =1, measure Friedel pairs. One prescan is done. Then, if the reflection is not considered weak, a final scan is performed on the reflection and its Friedel reflection. Whichever is done first is determined by the current position of the goniometer; they are alternated to minimize goniometer motion. =8, Measure the Friedel reflection at the alternative negative Theta position (NN).
NON-EQUAL	Flag to enable non-equal test. =0, omit non-equal test =3, do non-equal test. Notes on the use and interpretation of the non-equal test: If the non-equal test is selected, two final scans are done in opposite directions with double the scan speed. The results are compared. The result appears in the output in code position 5. During input non-zero values will be reset to 3. =*, non-equal test was not called for. =0, non-equal test was acceptable. =1, non-equal test failed. The final scan was repeated and the non-equal test was acceptable the second time. =2, non-equal test failed the second time, too. The data is still output. The profile dump contains both scans; one in the odd dumps and one in the even dumps. The dumps are broken down as follows: BGL1=dumps 1 to 15, N(odd),BGL2=dumps 2 to 16, N(even) INT1=dumps 17 to 79, N(odd),INT2=dumps 18 to 80, N(even) BGR1=dumps 81 to 95, N(odd),BGR2=dumps 82 to 96, N(even) The odd set of values is compared with the even set of values on a statistical basis; if the difference between two corresponding values is more than one standard deviation, the scan is rejected. sigma(NEQL) = [N(odd)+N(even)]**0.5 The difference between e.g. BGL1 and BGL2 is significant if >2.85*sigma(NEQL). Thus the test is accepted as good if: [N(odd)-N(even)]**2 < sigma(NEQL)**2*2.85**2. For very low intensities this formula becomes unreliable; the minimum value for sigma(NEQL) equals 7.5. Under normal conditions the irreproducability indicated by a failure of the non-equal test signifies an instrumental error, possibly a mechanical failure due to friction, motor gain mismatch, noise burst, sticking shutter, etc.. Service may be necessary. Note that angular resolution is halved to 48 steps, while the actual recording speed is doubled.
PSI=
WORD	Alphanumeric parameter controlling the azimuth angle during data collection; allowable values are BISECT, AZIMUT, FLAT, NEEDLE or VECHOR. During input the default value is BISECT. BISECT in ZIGZAG mode means: do the scan in the bisecting position, PSI = 0. Note that the definition "bisecting" position depends on the way the crystal is mounted on the goniometer head. BISECT in FILE or SEPHKL mode means: do the scan in the PSI postion given in the list or by the operator respectively. AZIMUT means: after a single pre-scan at PSIST, make a number of final scans, at different azimuth positions as determined by PSIST, DELPSI and N using the formula: PSI=PSIST+n*DELPSI , where n increments from 0 to N-1. The same scan speed is used for all final scans.
N	Number of final scans
PSIST	Starting PSI value
DELPSI	Increment in degrees. AZIMUT in FILE or SEPHKL mode is as above except that PSIST is superseded by the PSI position in the list (FILE) or by the value given by the operator (SEPHKL). In the case of a twinned crystal, AZIMUT can be used to measure each reflection at two different azimuth positions, thus enabling overlapping reflections to be recognized. For applying empirical absorption correction using the SDP programs PSI and EAC (according to A.C.T. North, D.C. Philips and F.S. Mathews, Acta Cryst 24A,351(1968)) 37 measurements with PSIST=0.0 and DELPSI=10.0 should be done for up to nine reflections. This information can be used to calculate absorption correction curves and to apply the correction, if necessary. FLAT or NEEDLE means: measure using an azimuth position for which minimum absorption is calculated, as determined by the shape of the crystal and the way the crystal is mounted on the goniometer head. VECHOR: measure using an azimuth position for which minimum anisotropic split up is calculated, as determined by the program ANIVEC.
V1,V2,V3	The vector V is the direction vector normal to the plane of a thin flat crystal, or the direction of the needle, when the goniometer is in the zero position. In the case of a flat crystal, FLAT calculates the position of minimum absorption using an imaginary crystal with finite but small thickness having an infinitely large surface area. The sum of the pathlengths of the incident and diffracted beams is minimized as a function of azimuth rotation. If the minimum position is impossible due to a collision, the best compromise will be used. In the case of a needle shaped crystal, NEEDLE calculates the position of minimum absorption using an imaginary crystal of finite diameter but infinite length. The calculation is made as described above. In practice this option is only necessary if the needle direction differs substantially from the capillary direction (Phik-axis direction). The difficulty in this case is determining the direction of V. In practice, it is not possible to provide one way, which always reveals V. Therefore, three alternatives are provided for determining the components of V in the X, Y and Z direction, namely V1, V2 and V3. The three alternatives are: Position the goniometer to orient the crystal (and thus V) along the x, y or z goniometer axis . Use the geometry translations to calculate the vector as follows: 1. V is set in the direction of the primary beam, the x axis. Use ME to get the Eulerian position Theta, Phie, Ome, Chie. Now do EC with the following values: 90, Phie, Ome, Chie. 2. V is set in the horizontal plane, perpendicular to the primary beam, the y axis. Use ME to get the Eulerian position Theta, Phie, Ome, Chie. Now do EC with the following values: 90, Phie, (Ome+90), Chie. 3. V is set perpendicular to the horizontal plane, the z axis. Use ME to get the Eulerian position Theta, Phie, Ome, Chie. Do EC with the following values: 90, -Phie, 90, (90-Chie).
MODE=
WORD	Alphanumeric parameter with the values ZIGZAG, FILE or SEPHKL. The default is SEPHKL. WORD determines the way in which the reflections to be measured will be derived. Reflections lying outside of the selected Theta range will be ignored. SEPHKL : Separate measurement of a single reflection . The program requests an index and azimuth posit ion, it measures that reflection , then prompts for the next series of H,K,L and PSI, e.g.: CD0> DATCOL<CR> H K L PSI? 0 0 20 0<CR> 1 1 0 0 20 N**S** 0.00 4 25 200 25 H K L PSI? (etcetera) This mode may be used e.g. for doing the measurements required for absorption curves (a series of scans at various azimuth positions), to verify the crystal quality or to look at Renninger peaks for one reflection.
FILE	Reflections are taken from a file. The file of reflections to be measured must have been linked to logical unit 3 during startup (see Initiating the CAD4) or afterwards using GONCON. Of course, the reflections to be measured must have been put into this file using the command DATHKL (see Reflection list preparation) or may be created using a separate program, for which an example is included.
ZIGZAG	The indices of reflections to be collected are generated by a zigzag routine using the following parameters :
HMIN KMIN KMAX LMIN LMAX	Minimum and maximum range of each HMAX, index, inclusive.
HST KST LST	Active starting values of the indices. These values are updated by the program to represent the next index to be collected. They will normally be set before the start of the data collection (by the operator) to the minimum values given above. The command DATCOL does not reset them. During input, each of these is limited by its active respective range (from MIN to MAX).
SEQ	Alphanumeric parameter that determines the order in which the indices will be incremented. The first one selected will be the fastest moving index and the third one selected will be the slowest moving index. The possible values are HKL, HLK, KHL, KLH, LHK, LKH. During input, the default is HKL. This parameter should be chosen to minimize goniometer motion between reflections. The most efficient way is to go through reciprocal space as much as possible along the z axis, to minimize PHIK-rotations. Therefore the last index to be incremented should be of the axis which is closest to KAPPA=134.8 degrees (i.e. CHIE=90).
ABSENT=
NR	The number of absent conditions to be used. Each condition is composed of a combination of up to three primitive conditions out of the list given below. When a negative number is specified, only the reflections which are supposed to be absent are being measured. This serves to confirm ideas about the space group of the crystal under investigation. A quick data collection is generally sufficient in this case. During input NR may range from -6 to 6.
XN,YN,ZN	The array containing the absence conditions. For input, the array is organized into 6 rows by 3 columns. The default is no condition. The numeric value is stored in the array by the program; however, the mnemonic symbols should be entered on the terminal.     Keyword  Not collected if: H=0 HN2 H is odd HN4 H is not fourfold H<0 H>K H>L HN3 H is not three fold AH>AK absolute H greater than absolute K AH>AL absolute H greater than absolute L H+KN2 H+K is odd -HKLN3 -H+K+ L is not three fold K=0 KN2 K is odd KN4 K is not fourfold K<0 K>L K>H KN3 K is not three fold AK>AL absolute K greater than absolute L AK>AH absolute K greater than absolute H K+LN2 K+L is odd H-KLN3 +H-K+ L is not three fold L=0 LN2 L is odd LN4 L is not fourfold L<0  L>H L>K LN3 L is not three fold AL>AH absolute L greater than absolute H AL>AK absolute L greater than absolute K L+HN2 L+H is odd HK-LN3 +H+K- L is not three fold. HKLN2 +H+K+ L is odd Example: ABSENT = 1 H=0 KN2 All reflections with H=0 and K odd will not be measured. Notes: Conditions given on one line are logical AND's and conditions given on separate lines are logical OR's. ABSENT is only operative in the ZIGZAG mode. Conditions should be entered in sets of up to three separated by spaces terminated by <CR>. Not more than 6 sets may be entered. No empty lines should be entered.
INTCR=
REPTIME	Intensity control parameter =0, do not do intensity control.  =n, do intensity control after measuring n seconds of X-ray exposure time.  If input is negative, the value is reset to 60000 seconds. Intensity control is not available in SEPHKL-mode. If intensity control is selected, i.e. REPTIME=N (N unequal 0) the intensity control reflections are taken from the refdump list as stored. The psi value for these reflections are retained upon measuring during data collection. Even after reorientation the intensity control reflections will be measured with the azimuthal angle used initially. Selected intensity control will be done before data collection starts, during data collection and (only in ZIGZAG mode) after data collection is finalised.
SIGMI	The sigma(I)/I ratio required for intensity control reflections. Used initially to calculate the scan speed for each individual reflection. Subsequent measurements always use the same scan speed. If input is zero or negative, the value is reset to 2.5. The quality of the intensity control reflections should be safely better than the normal data collection reflections; for example use SIGMI=SIGMA/3. Reflections in the CRYSTAL file must be enabled for intensity control by means of the LCI command. I reflectons are used, F or * are not. Orientation control reflections may also be used for intensity control. LCS is used to reset the status of the scan information to permit remeasuring the initial intensity (for LCI and LCS see Status code operations). 1: Following the commands DATCOL and DATCON, orientation control is done first, then intensity control. SIGMI is used during this initial measurement to establish the proper scan speed parameter for each intensity control reflection. The same scan speed will be used for subsequent measurements. 2: If, during the initial measurement, the reflection is too weak, too strong, or the position is impossible, the intensity control status code is changed from I to F, thus rejecting the reflection. No other error message is printed at this time. If, after reorientation, the position becomes impossible, the same action will be taken. 3: During subsequent intensity control checks, the measured intensity is compared with the initial intensity. If the intensity has dropped by more than the fraction specified by FADING, data collection is halted, and the message LISTNR 'FADING'NICS/RSCING<FRACTION e.g.: 3 FADING 0/4000. <0.50 The operator must respond with a / to regain control or Q(uit) to return to command mode. Any other response will cause the message to be repeated. This is done because the terminal may be off during data collection. After the /, the program asks GO AGAIN? If answered with a Y or YES, the intensity control status code for that reflection is changed to F and data collection continues. If answered with N or NO, the program returns to command mode.
FRACTION	Intensity drop cut-off point. The fractional ratio of initially measured intensity to current intensity I/Io of a control reflection, below which data collection should be halted.
ORIENT=
REPCNT	Orientation control parameter.  =0, do not do orientation control.  =n, do orientation control after measuring n reflections.  (Includes intensity control reflections). Orientation control is not available in SEPHKL.
DEV-ANG	The maximum allowable angular deviation in any direction from calculated position for any scattering vector. If DEV-ANG is positive, orientation control will only be done on the orientation control reflections specified by the command LCO (see Status code operations) in the CRYSTAL file. If the measured deviation exceeds DEV-ANG, reorientation and recalculation of the orientation matrix will be executed. If the measured position of any scattering vector during the course of data collection deviates more than DEV-ANG from the calculated position, the output for this reflection will contain a 'D' code on position 2 (goniometer status) as a warning (section E.2, Output record explanation). If DEV-ANG is given a negative sign, orientation control checking is done more carefully. This option should be chosen for good crystals when a good orientation matrix has been achieved. Actual orientation control has been optimized to guarantee measurement being done at correct positions and to minimize the time spent for orientation control operation: - Every reflection having sufficient intensity is checked for proper centering in Omega by comparing the shift of the peak profile against DEV-ANG. If the shift is too great the output for this reflection wil contain a status code 'D'. The diffractometer will immediately position the orientation control reflection and check on these doing the complete centering procedure (see Procedure for centering reflections). If this proves to be shifted too much, reorientation and recalculation of the orientation matrix will be executed. The program then will return to the next reflection in data collection. - When N/2 reflections have been measured following the last orientation check, the next good (sufficiently intense) reflection is centered doing the complete centering procedure. If it has not shifted more than DEV-ANG, orientation control is delayed again by N/2 measurements. If it has shifted too much, the diffractometer will center immediately the indicated orientation control reflection(s). If this check points to a shift, reorientation and recalculation of the orientation matrix will be executed. The reason for this procedure is to avoid any waste of time by positioning to the reference control reflections. If there is no shift recognized on any reflection during data collection, no orientation reflection would be positioned and checked unless there is no reflection of sufficient intensity after N-1 measurements). Indicating a reflection for orientation control and/or reorientation in the CRYSTAL file must be done using the LCO command (see "Status code operations"). O: reflection used for orientation control and orientation redetermination. R: reflection used only for orientation redetermination. In orientation redetermination, each O and R reflection is recentered, and the orientation matrix is recalculated. When the value in the last column (the lenght of the difference vector between the real scattering vector and the one as calculated from the current R matrix) is greater than the value in the header of that column, the status of this reflection is changed to N and this reflection is omitted for further calculations. Notes: - Orientation control reflections may also be used as intensity control reflections. - Dump profiles are always written for all intensity control reflections and for non-weak deviating reflections. - When, after centering and redetermination of the orientation matrix, any index of the used reference reflection deviates more than 0.3 from its original value, data collection will be halted immediately and the message 'ORIENTATION' will be printed. In this case redetermination of the orientation matrix would be difficult and probably unjustified. The same message will be printed if there are only reflections in one plane left for redetermination of the orientation matrix. The operator must respond with a / to regain control or with Q(uit) to return to command mode. - Orientation control precedes intensity control following the command DATCOL or DATCON. See "Data collection start-up" for more detailed information on DATCOL start and DATCON.
BACKG=
BGSEL	Static background select parameter. =0 do not perform static background, i.e. do usual scan with background measurements on each side of the reflection. =1 do one static background measurement. The sign of the parameter BGDIST indicates whether the measurement is done at high or low theta side of the peak. =2 do static background measurements on both sides of the peak.
BGTIME	Static background time in seconds. When negative on input, it is the time for one static background measurement, rounded off on a multiple of 0.24 seconds. When positive on input, a calculation is made depending on the first and last dump of the PRESCAN data, how long to measure the background in order to optimize sigma(I)/I.
BGDIST	Relative position parameter where to measure the static background. When the width of the reflection is defined as A+B*tan(Theta), a new width is defined as: abs(BGDIST)+B*tan(Theta), and the background is measured at the endpoints of this width. If one static background measurement is selected (BGSEL = 1) the sign of BGDIST indicates whether the background measurement is done at high theta side (BGDIST positive) or at low theta side (BGDIST negative) of the peak.

Data collection start-up

Starting data collection

DATCOL is the data collection routine start command. It is normally used once per data set. Data records are stored on a disk. The disk file name is defined during startup of the CAD4 system following the CAD4 dialogue or using the GONCON dialogue just before the DATCOL command is entered.

The command DATCOL performs the following functions:
1. Writes to data collection output file a header section consisting of: Data collection control parameters,the CRYSTAL file information for each control reflection, Orientation matrix and wavelength values;
2. Sets NREFL, the output reflection counter to zero, sets NPIFL to zero, forcing a new index to be used. 3. Starts at the beginning of the list of indices in FILE mode.
4. Sets cumulative X-ray exposure time to zero.
5. Conducts data collection process and writes results to data collection output file.

Notes: - DATCOL does not reset zigzag parameters HST, KST, LST to the HMIN, KMIN, LMIN boundaries. - DATCOL will always add data to the data collection output file.

If data exist in this file new data will be appended. Then there will be an inconsistency in reflection number and the data reduction program will report this. If the file contained data on another crystal structure an editor has to be used afterwards to split the output file in two parts each one containing data of one structure only. Since this involves additional work especially on large files it is advised to avoid this unintended appending of data.

Continuing data collection

DATCON is the data collection continuation command. It is used when data collection has been interrupted and is to be restarted where it was left off. New data will be added to the old file.

DATCON will only start with intensity control measurement, if selected, in ZIGZAG mode.

DATCON also writes header section as in DATCOL (because parameter(s) may have been changed during the interruption).

DATCON does not reset, NREFL, NPIFL, X-ray time, H,K,L index pointer in FILE mode or the ZIGZAG parameter(s).

Data collection may be interrupted at any time, preferably using SR=XXX1 e.g. to: -change control parameters -add reflections to the FILE list using DATHKL -examine the data with the program DATAR or by using an editor -copy the output file onto magnetic tape, etcetera.

As long as the CRYSTAL file is not disturbed, DATCON will continue from where it left off.

The data may be examined with DATAR or simply listed. If data collection has been interrupted by others means than SR=XXX1, there is a possibility that the last measured reflection(s) has(have) not been written into the file. Therefore, the use of SR=XXX1 must be preferred when the data collection process has to be interrupted.

Preparation of a reflection list for DATCOL

The DATHKL command enables the operator to make a list of reflections to be used for data collection. This list is used when MODE = FILE. (See MODE=.) The data is entered into the file with the extension *.HKL which is attached to the program. Upon entering the command DATHKL the program prompts 'H K L Psi?'. The operator must supply the indices and azimuth angle PSI for one reflection. The program will continue to prompt 'H K L Psi?' until the operator types Q(uit) to return to command mode.

The program first requests, 'Extend the file?'. The operator must respond with 'Y' when extending the file. If the operator responds with 'N', the question "Create a new (version of the) file?" will appear. Upon typing "N" the question 'Extend the file?' reappears.
Examples:

CD0> DATHKL<CR> ! when starting in a file just created.
H K L Psi? 1 2 3 0<CR>
H K L Psi? 4,5,6,90.00<CR>
H K L Psi? Q<CR>
CD0>DATHKL<CR> ! create new file.
Extend the file? N<CR>
Create a new (version of the) file? Y<CR>
H K L Psi? 1 2 3 0<CR>
H K L Psi? 4,5,6,90.00<CR>
H K L Psi? Q<CR>
CD0>DATHKL<CR> ! when extending a file.
Extend the file? Y<CR>
H K L Psi? -1 2 -1 0<CR>
H K L Psi? -1,-1,-1,0<CR>
H K L Psi? Q<CR>
CD0>

Notes:
- The azimuth angle PSI is not always used in data collection, but it must always be given. In most cases it is given as 0.
- When MODE = FILE or SEPHKL, and PSI = BISECT the reflection is set in the specified PSI position. In contrast, when MODE = ZIGZAG and PSI = BISECT the reflection is set with PSI = 0.
- When MODE = FILE or SEPHKL and PSI = AZIMUT the operator specified PSI is used instead of PSIST as specified in DATCIN.
- When PSI = FLAT or NEEDLE the operator specified PSI is inactive.

Any type of H,K,L-file can be attached to the program, provided it has the correct structure, during startup of the CAD4 program or using the change file option GONCON.

Data collection input parameters

In section B. of this chapter, the meaning of the various parameters that control data collection have been described. A correct choice of the various input parameters will be of great influence on both the accuracy of the data to be collected and the total time necessary for the measurement.

References

As the contents of this section can not be comprehensive, it is strongly advised to read the according literature for more detailed information:

"International Tables for X-Ray Crystallography" IV, p.282, The Kynoch Press, Birmingham, 1974.

Furnas, T.C. (1957). Single Crystal Orienter Instruction Manual, General Electric Company.

Arndt, V.W. & Willis, B.T.M. (1966). Single Crystal Diffractometry, Cambridge University Press. Einstein, J.R. (1974). J. Appl. Cryst. 7, 331-344.

Young, R.A. (1972). "Strategies of Measurement", Abstracts of the Summerschool at Aarhus, "Experimental Aspects of X-ray and Neutron Single Crystal Diffraction Methods".

Werner, S.A. (1972). Acta Cryst. A28, 143-150.

Burbank, R.D. (1964). Acta Cryst. 17, 434.

Stout, G.H., Jensen, L.H. (1972) X-ray Structure Determination, Macmillan.

Woolfson, M.M. (1978) Introduction to X-ray crystallography, Cambridge University Press.

Ladd, M.F.C. & Palmer, R.A. (1985) Structure Determination by X-ray crystallography, Plenum, 2nd edition.

Glusker, J.P. & Trueblood, K.N. (1985) Crystal Structure Analysis, Oxford University Press, 2nd edition.

Optimum parameter selection
 
 

THLIM	The theta limits for a measurement must be chosen according to the purpose of the data collection to be done. If a complete data set is required, the maximum theta (MAX) should be chosen according to the wavelength used. Working with Cu radiation, MAX should be at least 55 degrees. Using Mo radiation, 25 degrees will give a complete set.  In many cases it may be advantageous to measure reflections in shells of theta. This can be accomplished easily by using the commands DATCOL and DATCON for individual theta shells. The minimum value of theta (MIN) is dependent on the size of the beam catcher mounted. Using the smaller beam catcher (fine focus tubes), MIN that can be reached is about 2 degrees. Working with the long crystal-detector distance and the standard Protein Beam Tunnel mounted, MIN will be about 45 seconds. The TH routine calculates and prints the maximum indices possible and the number of reciprocal volume units. This number is an approximation of the number of possible reflections in the shell specified. It is calculated taking into account the entire Ewald sphere.
SCAN	Correct choice of the various variables to be specified is very important as it will influence precision as well as speed of data collection. The task is to make an accurate measurement in the shortest possible time. All classical scan methods are possible: stationary-crystal - stationary-detector method moving-crystal - moving-detector method (Omega/2theta scan) For fast data collection in a rather limited range of theta (e.g. measurements on crystals of very large molecules) a stationary-crystal method can be advisable. For this purpose the "peak-top"-mode can be chosen (TYPE = negative, cf. section B.3 of this Chapter, scan parameters). For more accurate measurements of the integrated intensity in a wider theta range a moving-crystal method should be applied. Various values can be chosen for the coupling ratio between the detector and the crystal motion. The best ratio will be the one that allows the operator to work with the smallest possible aperture width, still collecting the total integrated intensity. No theory will be given here. The interested operator may read the literature mentioned above. To find good input values for DOMA, DOMB, APTA, APTB and TYPE, the operator should do certain measurements on the sample crystal. Available programs should be used for this purpose (see OTPLOT).
INT	The choice of all input parameters that control the intensity measurement influence time and accuracy of data collection. A great flexibility has been incorporated. It is worthwhile to spend some time selecting the correct parameters in order to achieve the results required.  If a sample crystal is reflecting weakly, SIGPRE should not be made too small (SIGPRE = 0 is special case), as this will result in too many reflections flagged "weak" (see INT= and Output record explanation). Those that do not intend to remeasure all reflections, but still want to have a good quality data set without spending much time to analyse the effect of SIGPRE, are advised to to use SIGPRE between 1 and 2. Think about the standard deviation SIGMA of the intensity measurement you want. Table XI.1 shows the influence of SIGMA on the total time necessary for a data collection. It indicates the values for NPI(1/scan speed) for two reflections that had 300 and 1800 counts intensity after the prescan as a function of various values for SIGMA.  Dependency of NPI for various values of SIGMA and INT.   SIGMA NPIa NPIb 0.01 100 9 0.02 25 2 0.03  11 1 a: reflection with prescan intensity 300 counts b: reflection with prescan intensity 1800 counts NPIPRE will normally be 1. Using 2 or 3 will result in finding more reflections that have the desired SIGMA (or even better) by just doing a prescan. Then no final scan will be done. The choice of the value for MAXTIME depends very much on the sample crystal and time the operator intends to spend for one complete measurement. MAXTIME will overrule SIGMA. DUMP will not influence the total time for data collection. Considerably less reflection data can be stored on the disk and tape if the whole profile is recorded. Without profiles each reflection takes 128 bytes (one byte per character); with profiles, however, 640 bytes are used. 1 Disk block contains 512 bytes. It will be nice sometimes to check on the profile of specific reflections in order to find out what the quality of this data is (see Printing selected portions from the data). Use of a good fitting method is recommended for processing the data.
FLAG	Measurements using balanced filters are only possible on old types of CAD4. Before doing any measurement with Ross filters, correct balancing should be done. If Friedel pairs are to be measured, think about the method that may save time. Measurements at the same positive theta side or at the negative theta side are possible, (see Data collection control parameters(FLAG=)) Note: If measuring on both sides of theta=0.0; please remind to align the detector position (see Alignment of the Diffractometer). Non-equal tests are recommended at any time. This option also excludes any error caused by an incorrectly working detecting chain. The intensities are summed. The operator is not sacrificing time by working with this option because it uses a scan speed twice as high.
PSI	Read the appropriate literature to use the result of an 'azimuth' measurement for empirical absorption correction. Using the options NEEDLE or FLAT will reduce the time required for data collection and/or produce more accurate data. Check carefully on the correctly defined vector components. Remember that numerical absorption correction after using NEEDLE or FLAT will need special care, which is not supported by the usual absorption correction programs available under SDP. In case of anisotropic mosaicity, the option VECHOR can be used with the vector components as determined with the program ANIVEC.
MODE	Choose the correct starting values for H,K,L (in many cases minimum values of H,K,L) in order to get a complete or unique data set.
ABSENT	Check carefully whether the time-saving systematic extinctions (such as those caused by centering) have been correctly indicated. Think about the minimum necessary set of data if you want to save time.
INTCR	Is the crystal deteriorating in X-rays? The value of FRACTION should be chosen accordingly. Values down to 0.6 will generally allow reliable scaling of intensities.
ORIENT	Check if DANG has the correct sign. Use control reflections the position of which fit very well with the orientation matrix. Try using just the control reflections in LS.
BACKG	When the static background option has been chosen, carefully check the DOMA parameter in order to obtain the best possible Intensity and sigma intensity. Note: Before starting DATCOL print all data collection control parameters using DATCIN and check whether everything has been prepared as you want.

Check list for starting or continuing data collection

It is assumed that the goniometer is aligned properly, the radiation detection settings, the filter factor, the dead time parameter have been entered correctly and primary and secondary collimators are chosen in accordance with the size of the crystal and with the requested background level. The list given below is intended to avoid most of the common errors at data collection startup.

Check list DATCOL or DATCON:

a. Choose the proper operating tube load. Update the text string with the correct HV and tube current.
b. Print the current orientation matrix using RO (or using LS if the standard deviations are required).
c. Print the list of reflections using LO and specifying the line number range.
d. Verify whether the intensity check reflections have been marked with I (preferably 3 reflections).
e. Verify whether the orientation check reflections have been marked with O (at least 2 reflections).
f. Verify whether the reorientation control reflections have been marked with R (also those marked with O will be used).
g. Verify the file assignments using FILES. Assign a new output file for each structure and also if a few records in the current output file are of no further value. The maximum file size will be approximately 15,000 reflections (or 3000 reflections if profiles are stored).
h. Verify the number of free blocks on the output device you wish to use. 4 Reflections can be written into one block; if profiles are taken 0.8 reflections per block.
i. Check the amount of diskspace for the LOG-file.
j. Set the correct switch for output; SR=7600 selects all output.
k. Print the DATCIN parameters.
l. Check the water level if a closed cooling circuit is used for cooling the X-ray tube.
m. Start the data collection by the command DATCOL or DATCON. After taking all possible precautions it is advised to await the printout of the first few reflections and to verify their significance.

When the data collection is finished, the psi measurements for absorption correction should be done (if required). Hereafter, it can be tried to get better cell dimensions, for example by using SET4 and CELDIM.

Data collection output parameters

Output record format

The output of the data collection program is placed in the data collection file on the disk. The output is organized on the disk in records of 64 ASCII characters (64 bytes) and 8 records per block. One block contains 512 bytes of information. Characters 1 and 2 of each record contain a LineFeed and a blank, characters 63 and 64 contain a blank and a Carriage Return. Characters 3 and 4 of each record are used to identify the record type. This set of records comprise an output document which describes the entire data collection process without compromise. It includes the profile of each reflection (optional, and not represented as such), the description of the control reflections and the data collection control parameters.

Output record explanation

Type 0: Information about a single line in the CRYSTAL file describing a control reflection. (See the Reflection list).
 

Listnr	The line number in the CRYSTAL file. (between 1 and 25)
h,k,l	Indices of the reflection
HTAOIS	Reflection status codes
Theta	Theta angle of the reflection
Phik	Phi angle in Kappa geometry
Omk	Omega angle in Kappa geometry
Kappa	Kappa angle
Npi	Scan speed and attenuator status
Scan	Scanwidth
Int	Nett intensity

Type 1 : Minimum information about a measured reflection.
 
 

Nrefl	Reflection output counter
h k l	Indices of the reflection
Code	6 characters:
Char 1	Type of reflection  I - Intensity control reflection. (Orientation control reflections are not output.) N - Normal data collection reflection. S - Static background data collection reflection. More information in record 19.
Char 2	Goniometer status.  * - No problem with goniometer position.  C - Position impossible due to predicted collision.  D - Shift of this reflection more than DANG (read section B.3 of this Chapter, ORIENT=).  X - Position impossible, CHIE > 100 deg.
Char 3	Balanced filter indicator.  * - Balanced filter method not used.  A - Balanced filter A was used for measurement  B - Balanced filter B was used for measurement
Char 4	Intensity status.  * - Normal intensity  W - Weak intensity, [SIGMA(pre)>SIGPRE or SIGMA(final)>SIGPRE].  S - Strong intensity, with a count loss in the peak of more than 1%.  T - Too strong intensity. Even with attenuator set, count loss in the peak of more than 1%. May occur if scan speed is 16.48 (NPI=1) or is predetermined. Buffer counter overflow may have occured. Buffer counter overflow occurs at more than 1.024*10**5 counts/sec. Dead-time losses should be avoided below 5*10**4 counts/sec, by using the correct dead-time correction (see Chapter XIII of the printed CAD4 manual).
Char 5	Non-equal test indicator.  * - Non-equal test not used.  0 - Non-equal test was good.  1 - Non-equal test was repeated, the second time it was good. 2 - Non-equal test was repeated, the second time failed also. The results of the second test are placed in the output.
Char 6	Minimum absorption position status.  * - No minimum absorption settng.  0 - Measured at minimum absorption position.  1 -9 Minimum absorption position cannot be reached due to a predicted collision. Psi is set back at the nearest possible position towards the bisecting position n times 10 deg (n between 1 and 9).       .
Psi	Actual Psi-value used during data collection.
Npi	Scan speed parameter of 16.48/npi deg/min. A minus sign indicates that the attenuator was set.
Bgl	Background intensity left. Sum of dumps 1-16
Int	Total intensity over the peak area. Sum of dumps 17-80
Bgr	Background intensity right. Sum of dumps 81-96

Type 2 : Additional information about a measured reflection.
 

Nrefl	Reflection output counter
Theta Phik Omk Kappa	The goniometer position for center of scan in degrees as calculated from the orientation matrix. Phik, Omk refer to angles in Kappa geometry
Width	Omega scan angle in degrees for the entire scan including background areas. Width is negative if final scan direction is abnormal (i.e. from positive to negative Theta).
Xrayt	Cumulative X-ray exposure time during data collection in seconds
Fridl	first 2 characters: NFRIDL, last character: APC
NFRIDL	0 No Friedel pair measured  1 first Friedelpair with positive hkl  2 second Friedelpair with positive hkl  4 first Friedelpair with positive hkl at pos theta  8 second Friedelpair with positive hkl at pos theta  -1 first Friedelpair with negative hkl  -2 second Friedelpair with negative hkl  -4 first Friedelpair with negative hkl at neg theta  -8 second Friedelpair with negative hkl at neg theta cycle of measurements is e.g. +1, -2, -1, +2; or e.g. +4, -8, -4, +8 APC, Alternative Position Code is an integer in the range 0 - 9. The scheme shows how in DATCOL 'alternative' positions are searched for.

Click here to see a full description (drawing) of the output format of the CAD4.DAT file
Type 3-10 : 96 step profile dump.
 
 

Nrefl

Reflection output counter

Dumpi

The profile is always from negative (dump1) to positive (dump96), regardless of the direction of the scan. The normal scan direction for the final scan is from negative Theta to positive Theta. Each record contains 12 dumps, records type 3-10 are always together. For DUMPFL = 1 the dump values contain 4 characters (format i4, maximum 9999), for DUMPFL = 5 each dump value has 5 characters (format i5) and for DUMPFL = 6 a hexadecimal value is written (format z5). In case of DUMPFL 5 or 6 there are no record and reflection numbers in the record. Note: Angular resolution is only 48 steps when doing the non-equal test.

Type 19: Learnt profile or static background measurement output record.

Learnt profile output record:
 
 

Nrefl	Reflection output counter
Netti	Nett intensity divided by Npi
Sigmi	Sigma nett intensity divided by Npi
Fit	Goodness of fit between the expected and true nett profile
Fitint	Net intensity from fit divided by Npi
Fitsig	Sigma intentity from fit divided by Npi

If in record 1 code1 equals S, then record 19 contains information about a static background measurement.
 
 

Nrefl	Reflection output counter
Finet	Nett intensity from static background measurement
Sigmi	Sigma intensity from static background measurement
Res	Sigma(measured) / Sigma(wanted)
Timl	Time spent in background left (unity is 0.24 seconds)
Timp	Time spent in the peak scan
Timr	Time spent in background right

Note: Bgl, Int and Bgr in record 1 contain the number of counts collected during Timl,Timp and Timr respectively

Type 21-27 Datacollection parameters

Type 31-32: Orientation matrix, wavelength and attenuation factor.
 
 

R(3,3)	Orientation matrix
Flam1	Wavelenght alpha1
Flam2	Wavelenght alpha2
Atn	Attenuation factor

Program to print selected portions from the data collection file

Editor programs have almost all the functions required to search for selected sequences. The command DATAR enables the user to print selected portions of a data file on the CAD4 console terminal or to fill the HKL file with indices selected. DATAR is started by entering DATAR in response to CD0> prompted by the CAD4 program. DATAR prompts the question 'Option(s) :' to indicate that it is ready for a new command. The following commands are allowed:

Help TEXT is printed with an explanation of the command line format.
 
 

Print command line

This command may contain a number of selection criteria out of the following options:

 
 

/N X,Y	select reflections in which NREFL is between X and Y.
/R X,Y	select reflections with record type(s) between X and Y.
/A X,Y	select reflections with azimuth angle Psi between X and Y
/S X,Y	select reflections in which the scan speed NPI is between X and Y
/T X,Y	select reflections in which the theta angle is between X and Y
/I X,Y	select reflections in which the net intensity is between X and Y
/H X,Y	select reflections in which index H is between X and Y
/K X,Y	select reflections in which index K is between X and Y
/L X,Y	select reflections in which index L is between X and Y
/CAAAAAA	(AAAAAA represents the 6 character code word) select records in which the specified code is found. This only works in records type 0 and type 1. 6 ASCII characters should be given. If no selection is wanted, a dot '.' must be typed
/P	If profile information is present, that profile is printed as in program SCAN, for reflections of which other output is selected. The option /P will suppress the output of selected records of type 3 till 10, the profile records
/F X	Dump selected indices and PSI in FILHKL. Enter X if output is wanted.
/*	If you want to continue in the datafile
Q	To exit from DATAR and to return command to the CAD4 program.

Examples:

Select and print records 1 to 10 inclusive of reflection 9-20.

Option(s) : /N 9 20 /R 1 10<CR³

  1    9    0    0   -4 N*****   0.00  -7    18  38079     9
  2    9 -12.168 -125.887   -3.037  -28.065 -3.032    868 -1
  3    9    1   1   0    1   3   2    0   1   2    1   0   2
  4    9    1   0   2    1   2   0    0   3   3    1   3   1
  5    9    4   0   4    2   9   6    9  20  17   27  26  39
  6    9   44  40  48   57  64  74  127 200 529 177043096992
  7    9 817170644312 1856 825 416  284 178 125   77  68  84
  8    9   74  36  34   19   6   5    3   2   4    2   2   0
  9    9    0   0   0    1   1   0    0   0   0    0   1   1
 10    9    0   0   1    0   1   2    1   0   0    1   0   1

Option(s) :

Select all records of reflections 9-20 and print records 1, 2 and the profile.

Option(s) : /N 9,20 /P<CR³
    1    9    0    0   -4 N*****   0.00  -7    18  38079     9
    2    9 -12.168 -125.887   -3.037  -28.065 -3.032    868 -1
                        11
                      21561
                   113232124211
              1246803290364605151
215132132344465945458791581222031562011002013111  -1 0 7  -1 T 4  46
  1    10    0    0    4 N*****   0.00  -7     6  38387    11
  2    10  12.168 -125.887   21.298  -28.065  3.032    932  2

CD0> DATAR<CR>

Option(s) :

  The profile of the reflections is printed in 48 dumps. For an explanation of the profile printed see Optional Terminal Output. Printing can be interrupted by setting SWITCH (XXX1). This becomes effective after the current reflection and the next one have been printed.

  In the following example printout of profile only of weak reflections with reflection number in the range 1-300 is selected.

CD0> DATAR<CR>
Option(s) : /N 1 300 /C...W.. /R 3 10 /P<CR>
                       1
215132132344465945458791581222031562011002013111  -1 0 7  -1 T 4  46
Option(s) : 1<CR>
Option input syntax error
Option(s) : Q<CR>
CD0>