xs:alternative and xs:assert are not supported (document marked invalid)

[LordOfDragons]

Steps to reproduce:

• Write an XSD
• Inside an element bring up completion popup and select xs:alternative
• Tag is highlighted as error indicating that xs:alternative is not allowed which is wrong: xs:alternative can only be used inside an element

The same for xs:assert:

• Write an XSD
• Inside a complexType bring up completion popup and select xs:assert
• Tag is highlighted as error indicating that xs:assert is not allowed which is wrong: xs:assert can only be used inside a complexType

In both situations the completion popup correctly proposes the tags to be inserted but the syntax checker rejects them as invalid. Furthermore XML validation/completion using such XSDs fail altogether since the XSD is incorrectly parsed.

These are though two important tags to create more complex XSDs allowing some kind of data validation/completion instead of only structure validation/completion.

[angelozerr]

I think it is the same issue than #222

[LordOfDragons]

So if I get this right you are blocked by Xerces and it's not slated to be fixed in the foreseeable future? In that case it would be nice to mark somewhere in the docs this will never be done and as a consequence remove the support for completion proposal of all the tags that will never be supported. Either fixing it or totally dropping these tags would be okay just not mixing them causing confusion.