Our TEI specification documents (for elements, attribute classes etc.) are validated using NVDL, because they contain a range of external content such as RNG and Schematron which needs to be validated with non-TEI schemas.
An example document would be this one:
which is validated using this:
Some time during the lifetime of Oxygen 16.1 (we think), this stopped working properly; now when we validate, we get the following error:
Attribute @xsl:dummy-for-xmlns is not allowed on element <xsl:stylesheet>
which relates to this schema, linked from the nvdl file:
The handling of the isosch file in Oxygen seems to involve some processing which triggers the error.
Does anyone know why this might be happening, and what we can do to avoid it?
All help appreciated,