Schema: attributes restriction not supported in |-expressions?

This works:

nodes.doc.content = '(block | whatever)+'

while this:

nodes.doc.content = '(block | whatever[level=1])+'

gives you: SyntaxError: Invalid content expression

Is this by design as of today?

Attribute constraints should go outside of the parentheses, which is bad, but they are going away entirely so please don’t start relying on them.

Ok, thanks.