HP 1650B Programming Reference Manual page 245

selector
The TTRace selector is used as part of a compound header to access the
settings found in the Timing Trace menu. It always follows the MACHine
selector because it selects a branch directly below the MACHine level in
the command tree.
Command Syntax:
Example: OUTPUT XXX;":MACHINEl:TTRACE:GLITCH 'ABC', '....****I"
HP 1650B/HP 16518
Programming Reference 16-3