Library /sys$common/syshlp/ncphelp.hlb SET, LINE, STREAM TIMER milliseconds  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Applies only to DDCMP CONTROL lines.  Specifies the number of
 milliseconds a tributary or half duplex remote station is allowed to
 hold the line.  The number of milliseconds must be a decimal integer
 up to a maximum of 65,535.   The default is 1000 (1 second).