Hello

This might be quite unusual, so I don't expect a quick answer. Due to
a bug in biblatex I need a field in certain Bibtex entries empty, but
ALWAYS present.

By default Emacs kills empty fields when the function
bibtex-clean-entry is called. Is it possible to exclude a certain type
of field from deletion?

A more detailed description of the problem:

Biblatex knows the field "subtitle". If this field is not present in
InCollection entries, it is added via crossref from the corresponding
Collection entry. But this field, then, has the wrong value, since it
is the Collection's subtitle, not the InCollection's. So, the output
is spoiled. An empty subtitle field in the InCollection entry is a
workaround until this is fixed by the developer. But this makes the
function bibtex-clean-entry unusable unless it can be told to leave
empty subtitle fields in InCollections.

Greetings

Sven