Library /sys$common/syshlp/ncphelp.hlb SET, LINE, DEAD 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 between polls of one of the set of dead tributaries.
 The milliseconds value must be a decimal integer up to a maximum
 of 65,535.  The default is 10000 (10 seconds).