Hi Vladimir

Thanks for the explanation.  I didn't understand the semantics of override before  your explanation.  I get the gist of what you are saying and it explains the ambiguity errors I was getting in my toolset before I added these statements. The override  for searched-lib-generator makes sense.  What about prebuilt?  What's the motivation for:

generators.override builtin.lib-generator : xyz.prebuilt ;

Assuming $(xyz) = gcc , is gcc saying that it doesn't want the unix rule for prebuilt but rather builtin.lib-generator.prebuilt ?

Thanks for your help.  I'm sure there will be another fledgling toolset developer who will benefit.

Regards,
Mark