$ZST[EP] contains a string value specifying the default action for the ZSTEP command. $ZSTEP provides the ZSTEP action only when the ZSTEP command does not specify an action.

$ZSTEP initially contains the the value of the $gtm_zstep environment variable or string "B" if $gtm_zstep is not defined; note that the default "B" causes the process to enter direct mode. $ZSTEP is a read-write Intrinsic Special Variable, (that is, it can appear on the left side of the equal sign (=) in the argument to the SET command).

Example:

GTM>WRITE $ZSTEP
B
GTM>

This example displays the current value of $ZSTEP, which is the default.

Example:

GTM>SET $ZSTEP="ZP @$ZPOS B"

This example sets $ZSTEP to code that displays the contents of the next line to execute, and then enters Direct Mode.