For example, under our analysis, the tag 'VBG' has the features [+V, +N, -tense,en], tag 'VBD' [+V, +tense(past), -en], and 'VB' [+V, -tense(finite), -en].
since we do not consider the tense feature to be a structural feature, we do not distinguish 'VBD' from 'VB'; since N(ominal) is a structural feature, 'VBG' remains distinct from both 'VBD' and 'VB'.