variables prefix - ?variable vs. $variable

sometime ago I arose a possible issue about the usage of '?variable'  
style syntax vs. '$variable'  (i.e. clashing with SQL interface usage  
of '?' for
'placeholders and bind values' )

http://lists.w3.org/Archives/Public/public-rdf-dawg/2004AprJun/ 
0797.html (see second part of the message)

and I got a reply

http://lists.w3.org/Archives/Public/public-rdf-dawg/2004AprJun/ 
0802.html (see last part of the message)

but I still do not see any mention about the issue/problem (or how it  
could be solved/addressed) into the current BRQL draft

http://www.w3.org/2001/sw/DataAccess/rq23/

it seems Tucana iTQL uses '$' sign explicitly for variables - we do  
similar escaping into our current RDQL implementation for *DBC bindings

what is other people feeling about this? any other implementation  
experience?

or any chance to get '$' symbol accepted as a synonym for '?' symbol in  
the BRQL spec?

Alberto