Use of the ROFF field has been effectively deprecated since 1998, when its functionality was taken over by the cleaner ESLO/EOFF mechanism. ROFF was mainly kept for compatibility reasons.
I am sorry for the inconvenience caused by this change.
However, I think that not having many users being affected might be related to the ROFF deprecation 17 years before.
All this has not been adequately reflected in the Record Reference Manual, for sure. In the current documentation (that is part of the sources), field types are correct.