Get access to the xml: attribute groups for xml:lang
as declared on 'schema' and 'documentation' below
This type is extended by all types which allow annotation
other than <schema> itself
This group is for the
elements which occur freely at the top level of schemas.
All of their types are based on the "annotated" type by extension.
This group is for the
elements which can self-redefine (see <redefine> below).
for all particles
for element, group and attributeGroup,
which both define and reference
'complexType' uses this
Overrides any setting on complexType parent.
Will be restricted to required or forbidden
Not allowed if simpleContent child is chosen.
May be overriden by setting on complexContent child.
group type for the three kinds of group
Can be restricted to required or forbidden
We should use a substitution group for facets, but
that's ruled out because it would allow users to
add their own, which we're not ready for yet.
base attribute and simpleType child are mutually
exclusive, but one or other is required