Syntax of "global" attribute on "attribute" element

[James Clark <jjc@jclark.com>]

The "attribute" element has a "global" attribute with values "true" or
"false", indicating with it matches

  att="..."

or

  ns:att="..."

Can we find a syntax that makes it more obvious what the semantics are?
Maybe something like

 form="prefixed"|"unprefixed"

Any suggestions?

James