The TMARK Command [MLEPC]

The TMARK command is used to place a tape mark on the control tape to be used as a reference point when rewinding the tape. This command is valid for all machine types but may not be available on specific machines.

There are two different methods for specifying a TMARK on the tape. The first method involves outputting a rewind stop code along with an optional end of block symbol and any leader or trailer required. A TMARK message can be written to the verification listing indicating that a TMARK block has been output. A similar message can be output to the tape to inform the operator of the same thing.

The second method is to use a register identical in format to the sequence number register except for the register letter. The post-processor will simply replace the sequence number letter with the TMARK letter when outputting the command block.

The syntax for the TMARK command follows:

\textbf{TMARK}\;\textbf{/}\;\begin{pmatrix}\!\begin{array}{l}\textbf{ON}\\\textbf{OFF}\end{array}\!\end{pmatrix}

\textbf{TMARK}\;\textbf{/}\;\begin{pmatrix}\!\begin{array}{l}\textbf{AUTO}\\\textbf{NEXT}\end{array}\!\end{pmatrix}\,\bigl[,\mathit{value}\,\bigr]

\textbf{TMARK}\;\textbf{/}\;\mathit{value}\,\bigl[,\mathit{count}\,\bigr]

The first format, ON/OFF, can be used to start and stop the outputting of tape marks on subsequent blocks of tape. Coding TMARK/ON will resume the last mode specified for TMARK. Coding TMARK/OFF will disable further output of tape marks until another TMARK command is coded.

The second format is used to output a tape mark immediately, or whenever possible operator intervention is required. The TMARK/NEXT command will cause a tape mark block to be output on or prior to the next command block. The TMARK/AUTO command will cause a tape mark to be output whenever a tool change, STOP or OPSTOP occurs. If a value of n is defined, a tape mark will be outputted each n block.

The TMARK/value format will cause the post-processor to output a tape mark block with the specified value. If the machine uses the rewind stop method for TMARK, then the value will be ignored. An optional count value can be specified to force a tape mark every count blocks.