@oals Well, there are two different thing we can talk about.
Anonymous
With the thing we've labeled "GA–NO conversion" on this site, we have の rather than が marking a subject in a relative clause.
Anonymous
But の can't replace を in a relative clause.
Anonymous
The other thing is when you have a verbal noun, as in chocolate's comment:
Anonymous
As mentioned by @oals (only with 'real' nouns), maybe you're thinking about something like 絵を描く→絵画の製作, ピアノを弾く→ピアノの演奏, 本を買う→本の購入 etc, no? — chocolate2 days ago
Anonymous
In 絵画の製作 and 本の購入, we don't have relative clauses, so it's something else.
Anonymous
1:15 AM
Instead we have noun phrases where the head noun is a special kind of noun called a verbal noun (the sort where you can add する and it makes sense).
Anonymous
And in this sort of noun phrase, the NP argument corresponding to a が or を argument in a corresponding full clause is instead marked with の.
Anonymous
But we can't use the same terminology for that because it's a different phenomenon.