IBM Professional Series User Manual page 303

RT: Use the RT command to restore terminal output from
an executing eMS command or one of your programs that
was previously suppressed by the HT command. The format
of the RT command is:
Usage Note: Program execution continues, and displaying
continues from the current point of execution in the
program. Any terminal output that is generated after the HT
command is issued and up to the time the R T command is
issued is lost. Execution continues to normal program
completion.
7 -130 VM/PC Users Guide