The .SET DATE and .SET TIME commands let you specify a date and
time to be inserted in your file when you issue the Substitute
flag pair, $$, with any of the appropriate date or time
parameters. .SET DATE also sets the date for the .DATE command,
which causes the date to appear in running heads.
Formats
.SET DATE d1 ,d2 ,d3
.SET TIME t1 ,t2 ,t3
Abreviated formats
.SDT d1 ,d2 ,d3
.STM t1 ,t2 ,t3
Additional Information:
explode
extract