The General Data Type Conversion routine converts OpenVMS
    standard atomic or string data described by a source descriptor
    to OpenVMS standard atomic or string data described by a
    destination descriptor. This conversion is supported over a
    subset of the OpenVMS standard data types.

    Format

      LIB$CVT_DX_DX  source-item ,destination-item

                     [,word-integer-dest-length]

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

2  –  Arguments

 source-item

    OpenVMS usage:unspecified
    type:         unspecified
    access:       read only
    mechanism:    by descriptor

    Source item to be converted by LIB$CVT_DX_DX. The source-item
    argument is the address of a descriptor pointing to the source
    item to be converted. The type of the item to be converted is
    contained in the descriptor.

 destination-item

    OpenVMS usage:unspecified
    type:         unspecified
    access:       write only
    mechanism:    by descriptor

    Destination of the conversion. The destination-item argument is
    the address of a descriptor pointing to the destination item.
    The destination descriptor specifies the data type to which the
    source item is converted.

 word-integer-dest-length

    OpenVMS usage:word_unsigned
    type:         word (unsigned)
    access:       write only
    mechanism:    by reference

    Length in bytes of the destination item (when that item is a
    string) that has been converted by LIB$CVT_DX_DX, not including
    any space filling. The word-integer-dest-length argument contains
    the address of an unsigned word containing this length.

    If the destination string is truncated, the returned length
    reflects the truncation. This word can be used by the calling
    program to determine if truncation has occurred or to extract
    the exact length of the string when the string contains space
    filling.