Library /sys$common/syshlp/dbg$help.hlb DEBUG, Built in Symbols, %PROCESS PID  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    When specifying a process identifier (PID) in a debugger command
    string, you must precede the PID with the symbol %PROCESS_PID.

    Example:

    all> CONNECT %PROCESS_PID 258001B6