filespec

    OpenVMS usage char_string
    type          character string
    access        read only
    mechanism     by reference
    Address of file or directory specification from which to read the
    symbols (zero-terminated ASCII string).

 options

    OpenVMS usage longword_unsigned
    type          longword (unsigned)
    access        read only
    mechanism     by value
    Indicates type of symbol file and flags, as shown in the
    following:

    Flags                  Effect

    SDA_OPT$M_READ_FORCE   read/force <file>
    SDA_OPT$M_READ_IMAGE   read/image <file>
    SDA_OPT$M_READ_SYMVA   read/symva <file>
    SDA_OPT$M_READ_RELO    read/relo <file>
    SDA_OPT$M_READ_EXEC    read/exec [<dir>]
    SDA_OPT$M_READ_NOLOG   /nolog, suppress count of symbols read
    SDA_OPT$M_READ_        <file> or <dir> given
    FILESPEC
    SDA_OPT$M_READ_        return status, without signaling errors
    NOSIGNAL

 relocate_base

    OpenVMS usage address
    type          longword (unsigned)
    access        read only
    mechanism     by value
    Base address for symbols (nonsliced symbols).

 symvect_va

    OpenVMS usage address
    type          longword (unsigned)
    access        read only
    mechanism     by value
    The symbol vector address (symbols are offsets into the symbol
    vector).

 symvect_size

    OpenVMS usage longword_unsigned
    type          longword (unsigned)
    access        read only
    mechanism     by value
    Size of symbol vector.

 loaded_img_info

    OpenVMS usage address
    type          longword (unsigned)
    access        read only
    mechanism     by reference
    The address of $LDRIMG data structure with execlet information.