> generate a reference to a symbol other than 'foo'.

 >> any why it is used in NetBSD?

> For backwards compatibility.

Do you mean that ALL/MOST programs/packages built for older NetBSD
releases should work without recompilation with newer NetBSD versions
and NetBSD releases are ALWAYS binary backward compatible with older
releases?

Or at least there is such goal?

If no, It whould be interesting to see/hear more details.

-- 
Best regards, Aleksey Cheusov.