Library /sys$common/syshlp/ncphelp.hlb SET, CIRCUIT, STATE circuit-state  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Specifies the circuit's operational state. There are three
 possible states:

 OFF       The circuit is not in use.

 ON        The circuit is available for normal use or service
           functions.

 SERVICE   The line is available for service functions only.