Numbers in library names

[Lassi Kortela]

> To correctly attach marks (in the R6RS syntax model) to the imported 
> identifiers, the expander needs marks associated with the library name 
> (and takes the marks of the last name part, which, therefore, must be an 
> identifier).
Where does the decision to take the last library name part come from?

Only Chez Scheme? Any other implementations? Does R6RS address this?

Why not take the first library name part instead of the last? In 
practice, a numeric last part is useful and is already widely used. It's 
far less likely for a numeric first part to be useful.