>Ehm, that's the best example around!

Ehm, thats probably the only working Firebird 1.0/InterBase6.0 example around
that
actually works.

Other examples would be embedded in the source code, since filters are also used
inside the engine to filter from blr->text etc.

See:
/jrd
-> blb (blob handling routines; storage and retrieval of blobs)
->blf (handles blob filters; determines if there is a blob filter for a blob and
filters the blob
through it)
-> filters (internal filters for printing system relation blobs)

Regards
Paul