On initialization, SDA reads the universal symbols defined by
    SYS$BASE_IMAGE.EXE. For every procedure descriptor address symbol
    found, a routine address symbol is created (with _C appended to
    the symbol name).

    SDA then reads the object file REQSYSDEF.STB. This file contains
    data structure definitions that are required for SDA to run
    correctly. It uses these symbols to access some of the data
    structures in the crash dump file or on the running system.

    Finally, SDA initializes the process registers defined in the
    SET PROCESS command and executes a SET CPU command, defining the
    symbols as well.