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scans, the limit checks are done only at the scan endpoints. For reciprocal spacescans, the motor positions do not necessarily change monotonically and so the motorlimits must be checked at each scan point. Since this checking requires a time-consumingloop at the macro level, you may choose to disable the feature if you are confidentyour reciprocal space scans will not send a motor outside the ranges defined bysoftware limits.Motor Scansascan motor start finish intervals timea2scan m1 s1 f1 m2 s2 f2 intervals timea3scan m1 s1 f1 m2 s2 f2 m3 s3 f3 intervals timemesh m1 s1 f1 intervals1 m2 s2 f2 intervals2 timelup motor start finish intervals timedscan motor start finish intervals timed2scan m1 s1 f1 m2 s2 f2 intervals timed3scan m1 s1 f1 m2 s2 f2 m3 s3 f3 intervals timeth2th tth_start_rel tth_finish_rel intervals timeThe argument motor (and m1 , m2 and m3 )isamotor number or mnemonic, such asth , tth , chi ,orphi . ascan , a2scan and a3scan are single-, two- and three-motorabsolute-position scans. mesh is a nested two-motor scan, where the first motor scansthrough its range at each point of the second motor’s scan. lup (or equivalentlydscan ), d2scan and d3scan are single- and two- and three-motor relative positionscans. The starting and finishing positions are given relative to the current position,and the motors are returned to their starting position at the end of the scan. Theserelative position scans are defined in terms of the absolute-position scans.The th2th macro is a special case of the d2scan that will scan the tth and th motors,with th moving half the range of tth .Its definition is,def th2th ’if ($# != 4) {print "Usage: th2th tth_start_rel tth_finish_rel intervals time"exit}d2scan tth $1 $2 th ($1)/2 ($2)/2 $3 $4’146 STANDARD MACRO GUIDE INTERIM WORK-IN-PROGRESS (8/16/01) NOT FOR GENERAL DISTRIBUTION