Phillip H. Griffin wrote:
> John,
>
> I do not have a clue what you mean when you use the term
> "EXTENDED-XER". I can find no mention of this term in
> any of the ASN.1 standards that XCBF and X9.84 reference.
EXTENDED-XER is what was earlier referred to as VXER (Variant XER).
That is just a name change. Use of it allows encoding instructions to
be applied (without an encoding instruction it does not differ from
BASIC-XER - the new name for what you would call XER). A single
encoding instruction can modify many of the XER encodings to use text
rather than empty element tags, to provide better alignment with XSD
encodings. There are also about 20 specific encoding instructions such
as BASE64 that perform specific functions in relation to XML encodings.
Probably the most important such encoding instruction is UNTAGGED, that
removes XML tags round things like a sequence of elements, or a choice
of alternatives, or a sequence of elements, but there are others that
are designed to support XSD-specific functionality, such as
DEFAULT-FOR-EMPTY and USE-TYPE and USE-NIL and USE-ORDER. Mainly, but
not exclusively, the encoding instructions have been developed to
support the mapping from XSD, and apart from BASE64, are probably not of
particular relevance to the XCBF work.
John L
