[Playlist] Schema files and element order

[Lucas Gonze]

Sebastian Pipping wrote:
> I did some math about the "unroll solution".
...
> For <track> that would be 8! = 40,320 combinations.
> For <playlist> that would be 11! = 39,916,800 combinations!
> So if that way really is the only way to teach XSD speaking
> XSPF then this should make clear why WXS/XSD is a bad choice
> for a XSPF schema.

Ok, so it's really not possible to do an XML Schema where the element 
order doesn't matter.  That's significant.

In that case I'm leaning towards abolishing or at least aggressively 
deprecating the XSD, since it declares stuff invalid which is really 
legal, and that will end up creating a separate dialect where element 
order matters.

I feel strongly that validators should not cry wolf.  It's so valuable 
to have developers care about what the validator says, and spurious 
errors motivate them to ignore the validator.  It's like a speed limit 
which nobody is intended to obey, which only creates disrespect for the 
law in the end.

However, performance is a critical issue.  Yahoo is using the schema to 
validate input files before storing them, which is (1) totally 
reasonable and (2) performance intensive.  To switch over to RNG the 
performance would have to be comparable.

Thoughts?

-Lucas