"For interoperability" and "must" don't mix

The last paragraph of clause 3.1 says:

# For interoperability, the empty-element tag must be used, and
# can only be used, for elements which are declared EMPTY.

But "for interoperability" flags a "non-binding recommendation", as
clause 1.2 says, and so doesn't mix with "must".  All other uses
of the phrase are associated with "should".

I recommend the following wording:

# For interoperability, the empty-element tag should be used, and
# should only be used, for elements which are declared EMPTY.

-- 
John Cowan	http://www.ccil.org/~cowan		cowan@ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)