Goals wrote:"The fourth principal part, while given in its neuter form in this book, is for regular transitive verbs the perfect passive participle, a fully declinable verbal adjective of the -us,-a-,-um variety (laudatus, -a, -um, ect - some uses of the participles will be explained in Chs. 19 and 23-24). Verbs lacking a perfect passive participle substitute the accusative supine (see Ch. 38 ), and some verbs like sum and other ntransitives substitute a future active participle (e.g. futurum = fututurus, -a, -um), while others like possum have no fourth principle part at all." p. 76
Why he gives the neuter form I am not sure, but my guess is in my earlier post.
Italic emphasis mine
Weird, how inconsistent. Why he doesn't just use the supine for all that have a perfect passive participle is beyond me. It's the same thing, without unnecessary complication.
Most standard dictionaries use just the accusative supine, or if they're brave enough, the masculine perfect passive participle. I've never seen anyone make such a distinction to differentiate between the two in listings before.~