Nodes with conll_deprel attribute COORD under coordinating conjunction (tag=C) or coordinating comma (tag=P) are marked with the is_member attribute (i.e. as conjuncts).

CoNLL2007 English data marks several other constructions with COORD. We don't consider these coordinations and therefore we don't mark these with is_member. For example:

A rather then B

A along with B

A instead of B

A as much as B

If is_member is set before, it is preserved.