A comment is a command line or part of a command line in DCL that is ignored by the CLI. Comments are marked with an exclamation point (!).
Consider the following command procedure, TEST.COM:
$ show time !This comment is ignored $! This entire line is ignored as well
Here is the result of running it:
$ @test 19-DEC-2018 11:19:38
The most important and obvious way to use comments is documenting a command procedure:
$ ! Copyright (c) 1987 Digital Equipment Corporation. All rights reserved. $ ! $ ! MONITOR.COM (Generate MONITOR recording file) $ ! $ ! This command file is to be placed in a cluster-accessible $ ! directory called SYS$MONITOR. At system startup time, for each $ ! node, it creates in SYS$MONITOR a MONITOR recording file, which $ ! is updated throughout the life of the boot. It also creates in $ ! MON$ARCHIVE, a summary file from the recording file of the $ ! previous boot, along with a copy of that recording file. $ ! Logical name definitions for both cluster-accessible directories, $ ! SYS$MONITOR and MON$ARCHIVE, must be included in SYSTARTUP.COM. $ !
Another use of comments is disabling a command line that is not needed now but may be needed in the future:
$! Uncomment the following command to start the OpenVMS Management $! Station server application. $! $!$ @SYS$STARTUP:TNT$STARTUP