unable to read source file file_specification

    Facility: DEBUG, VMS Debugger

    Explanation: Source lines from the file file_specification cannot
    be displayed because the debugger was unable to read the source
    file (represented as file_specification). The accompanying VAX
    RMS status message gives more information about the reasons for
    the source file not being opened.

    User Action: Examine the VAX RMS status message to determine
    the reasons for the source file not being read, and take the
    appropriate action based on that information.