XQFO: Unknown option parameters

[ChristianGruen]

The current option parameter conventions are:

4. It is not an error if the options map contains options with names other than those described in this specification. Implementations MAY attach an ·implementation-defined· meaning to such entries, and MAY define errors that arise if such entries are present with invalid values. Implementations MUST ignore such entries unless they have a specific ·implementation-defined· meaning. Implementations that define additional options in this way SHOULD use values of type xs:QName as the option names, using an appropriate namespace.

The obvious consequence is that wrongly typed or unsupported options are not reported as such:

serialize($node, map { 'format': 'html' })

I think we should still allow proprietary options, but raise errors when an option is neither defined in the specification nor supported by the given implementation. On the one hand, this will help users to spot typos (e.g., byte-order-mask or instead of byte-order-mark). On the other hand, options that are supported by one implementation will be rejected, which feels reasonable to me, as options usually change either the result, or the way how the input is treated.

If we believe that this change is too disruptive, we could tolerate entries with xs:QName keys.

[michaelhkay]

Incidentally, F+O §1.6 still refers to the "function conversion rules" by their old name, with a link to XP31.

[michaelhkay]

I'm inclined to agree that unrecognised bare strings should be rejected (but note this ends up being advisory, since implementations can always choose to recognize every string...). QNames and Q{uri}local strings should be accepted.

[michaelhkay]

I hit an interesting example today: I wrote a test that did:

csv-to-arrays("a,b,c,d,e,f|p,q,r,s,t,u", 
             map{'row-delimiter':'|',  'select-columns':1 to 3}) 

It's easy to forget that select-columns is allowed on parse-csv but not on csv-to-arrays. Perhaps we should change that; but in the meantime, silently ignoring the option isn't exactly helpful.