restricted use of Dot and DotDot

XQuery 1.0: An XML Query Language
W3C Working Draft 20 December 2001
and
XML Path Language (XPath) 2.0
W3C Working Draft 20 December 2001

Is there any reason why the syntax disallows (e.g.)
                ..[whatever]
but allows
              (..)[whatever]
and
    parent::node()[whatever]
?

That is, why is DotDot an entire step (with no opportunity for
StepQualifiers), rather than an alternative to 'Axis NodeTest'?

Ditto all the above for Dot.

-Michael Dyck