I think it is unecessary confusing to have both of the pairs
('Required', 'Optional')
and
('Required', 'Implied')
in the XSchema vocabulary.
>Choice (Frequency ("Required", "Optional", "ZeroOrMore", "OneOrMore"))
>Seq (Frequency ("Required", "Optional", "ZeroOrMore", "OneOrMore"))
>Ref (Element, Frequency ("Required", "Optional", "ZeroOrMore", "OneOrMore"))
...
>Required
>Implied
I know that 'Implied' is what is used within DTDs, but personally I find
'Optional' to be much more "to the point", I find 'Implied' quite
"mysterious".
Cheers,
Jarle Stabell