[Xcb] schema for xcb validation

[Mikhail Gusarov]

Twas brillig at 19:11:04 02.03.2007 UTC-08 when Josh Triplett did gyre and gimble:

 >> +grammar {
 >> +   start = XCB
 >> +
 >> +   XCB = element xcb {
 >> +      attribute header {text},
 >> +      attribute extension-xname {text}?,
 >> +      attribute extension-name {text}?,

 JT> Any way to add a constraint that says these go together, such that you must
 JT> have both or neither?

(attribute extension-xname {text},
 attribute extension-name {text})?,

should do the trick.

-- 
JID: dottedmag at jabber.dottedmag.net