Library /sys$common/syshlp/dbg$help.hlb DEBUG, Messages, NOCANMAIN  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 cannot cancel main image

    Facility: DEBUG, VMS Debugger

    Explanation: The user has requested that the main image symbols
    be canceled. This is an invalid operation.

    User Action: No action required - operation invalid.