Disallow obsolete attributes/values

Since CSL 1.0, the schema has been rewritten to include separate definitions for dependent and independent styles. As a result, we can be more specific with regard to the attributes and attributes values allowed for each type. We should probably make this change in CSL 1.1 to prevent style from becoming invalid. The attributes/values affected:

• for cs:link, “independent-parent” (independent styles) and “template” (dependent styles)
• for cs:style, “class”, and any of the style options (dependent styles)

These can all just be stripped from styles with the next XSLT upgrade script, and removed from the schema.

[bdarcus]

And I just added a commit with the XSLT file. It currently only strips link elements with those two values, and updates the version number.

As you can see, it’s trivial.

https://github.com/citation-style-language/schema/blob/v1.1/tools/csl-update.xsl

[rmzelle]

And in the past the CSL project provided a XSLT schema to upgrade 0.8.1 styles to 1.0 (https://docs.citationstyles.org/en/1.0/release-notes.html#updating-csl-0-8-styles). I don’t know if we should offer that for 1.1 as well? …

We could; sure.

Maybe we can tag PRs that involve changes where styles/locales can/should be upgraded as such with a GitHub label? (just dropping attributes would be easy to do in XSLT)

(that might be handier than having to update an XSLT for each relevant PR that is merged)