[xml-dev] problem in using schema for schemas

[Takuki Kamiya <takuki_kamiya@bigfoot.com>]

Hi,

I have encountered a problem in using schema for schemas for XML
schema pre-processing.

I am using schema for schemas for pre-processing an XML schema
for syntax checking and possibe default-value contribution
before turing it over to my downstream schema processor.

The problem is that schema for schemas always contributes some
attribute values to certain elements (if none was present) which XML
Schema specification explicitly prohibits in some context.

For example, <element> under <complexType> or <group> may have
"ref" attribute. In such a case, for example, "nillable" property
is not allowed to be present as per section 3.3.3. However, schema
for schemas apparently not only tolerates it (which is actually ok),
but also suggests to contribute default value "false" if none was
sepcified.

I am not sure whether schema for schemas is intended for possible
use for pre-processing schemas (which I think is useful), but it
would be better if the PSVI can be correctly used for downstream
schema processing.

I could modify schema for schemas by myself locally, but noticed
it is normative. I think those default values that clashes with
explicit constraints had better be taken out from the schema for
schemas if there is any revision planned.

-Takuki Kamiya