Check whether a formula is already in OOXML storage format
is_ooxml.RdA formula is considered "already OOXML" if it contains at least one
_xlfn., _xlws., or _xlpm. token.
is_ooxml.RdA formula is considered "already OOXML" if it contains at least one
_xlfn., _xlws., or _xlpm. token.