binding in openmath

Can somebody clarify for me please the concept of bindings, as it relates 
to the OpenMath standard? Or at least point me to a documentation (other
than the draft, which I already read) explaining that? I am not sure
if this is the best forum, but the only other appropriate place was the
NAOMI newsgroup, and the postings there were more about new products,

Thank You,

Leonardo B. Lopes                                       leo@iems.nwu.edu 
Ph.D. Student                                              (847)491-8470
IEMS - Northwestern University              http://www.iems.nwu.edu/~leo

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