there are three states in the following matrix for which i cannot yet specify
the effective binding:
(ed = element default, cd = context default,
eb = element binding, cb = context binding)
default presence in attribute declaration
attribute
presence in
element -- -- | -- ed | cd -- | cd ed
---------------------------------------
| unbound | ed | cd | ? ? |
-- -- | | | | ? ? |
----------------------------------------
| | | | |
-- eb | eb | eb | eb | eb |
----------------------------------------
| | ? ? | | ? ? |
cb -- | cb | ?* ? | cb! | ? ? |
----------------------------------------
| | | | |
cb eb | eb | eb | eb | eb |
----------------------------------------
*: xml-dev discussion has implied that the context binding takes precedence,
but that would lead to capturing prefix bindings on included external entities
- which is not necessarily to be recommended. (see, for example, http://www.lists.ic.ac.uk/hypermail/xml-dev/9808/0152.html)
!: modulo the other ambiguities
i would suggest that the attribute declaration in the dtd should be afforded a
"lexical" scope which takes precedence over the dynamic scope of any bindings in
the element stream.
[19980810: i then went ahead and implemented the opposite, but i don't yet see
the choice as an essential issue, just so long as the choice is made]