There are two versions of the ISPEnv.schema, which one should I use?

The old version is included for legacy reasons only and should not be used for new installations, as it will not work with recent openLDAP servers. Beware if you plan to upgrade your schema, the two versions are slightly incompatible.

Please also note, that you are not required to use either of the supplied schema, as GNARWL does not depend on a specific schema.