Halliday & Matthiessen (2014: 380):
It is natural that the more lasting attribute should tend to have a classifying function. But the present participle as Classifier does not exclude the sense of ‘which is ... ing’, as in the rising/setting sun; and conversely, the past participle as Epithet does not always carry the meaning of ‘which has been ...’, since many such forms are in fact adjectives, as in a haunted house, a crowded train.
The same word may be now one, now the other: in Would you like a boiled egg? boiled is Classifier, ‘which gets boiled’, contrasting with fried, poached or scrambled; while in You must drink only boiled water here, boiled is Epithet ‘which has been boiled’.
In He got stuck in a revolving door, either interpretation is possible: Classifier ‘of the kind which revolves’, Epithet ‘which was revolving’ (cf. fast trains above).