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Just a comment on the use of “union” in this
way….. Obviously it provides a concise and elegant way of expressing
the allowed element content without repeating the enumerated values of the
PeriodEnum. However, in terms of processing the information, a union
generally implies a kind of “choice” semantics, whereas the
way it is used here the semantics are more like a kind of extension, or at
least the inverse of a restriction. For example, in Xpath 2 data model, when the element or
attribute node is defined via a union type, the typed value determination is determined by the type definition that actually validated the content
of the node. So in this situation the typed value type will either be
PeriodEnum or the anonymous type which appears in the union, depending on
whether or not the value was “T”. It will never be
PeriodExtendedEnum. If you modelled it the other way round with PeriodEnum as a
restriction of PeriodExtendedEnum t you would have to repeat the actual
enumerated values in the two definitions. However, the enumerations on
PeriodEnum would have to be a subset of the enumerations on PeriodExtendedEnum
or the schema would be invalid, so there would be protection against mistakes
being made as the schema evolves. A restriction approach more accurately reflects the semantics
although it has a slight overhead for whoever has to maintain the lists of
enumerations in the schema. Obviously it wouldn’t work for the
situation where you wanted multiple different “extensions” of the same
list. I don’t know how significant or otherwise the implied
semantics of union may be to the various applications which consume or produce
FpML, but this aspect is something to bear in mind. Regards, Pete From: valwg@xxxxxxxx [mailto:valwg@xxxxxxxx] On
Behalf Of Marc Gratacos We attempted to split the existing PeriodEnum into two:
PeriodEnum and PeriodExtendedEnum. The Extended list is a union of the
PeriodEnum and it adds the 'T' (term) value. See attached. Let me know
if you have any comments. Thanks
and Regards, Marc The information contained in either this email and, if applicable,
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