Definition of SPARQL variable pre-binding

[Holger Knublauch]

Hi,

(this question is motivated by the ongoing Data Shapes WG, but I don't 
speak on their behalf).

Jena and other APIs such as Sesame support the concept of pre-binding 
variables prior to SPARQL execution, using 
QueryExecution.setInitialBinding(). This is convenient to reuse 
parameterized queries, especially with blank nodes.

Question: is there any formal basis of this functionality, formulated so 
that it can be implemented by other platforms too? I can see that it 
populates the original bindings that are passed through the algebra 
objects, but what would be the best way to explain this by means of 
concepts from the SPARQL 1.1 spec?

Thanks
Holger