Concrete is only avant garde to the extent it is not subsumed by the hypothetical set we call "poetry." & then or thus or moreso the "hypothetical set" we call visual poetry -even tho its definitions may be broader- is restricted in the sense that it is another pleasure of the idiom. The avant garde (as opposed (literally) to the postavant (which DOES exist), to poets, painters, etc) defines itself (from without) by being an oppositional force. The Situationist anthology wrapped in sandpaper.

And to that extent the avant garde is bad. Mac Low's chance/deterministic pieces are bad to the extent they are poems (ask conventional poets!) but good if not incredible to the extent they are not. -while remaining w/in the definitions of the set-
An avant garde work wld not have borders w/in or around it The avant garde artist wld have to be in loathe of his subject
If the avant garde artist was a lover of poetry
he wld stay away from it

A binary alphabet wld halve to reflect that. Or the diastic selection wld dance to it, as the translation incl. color, it incl. setting, as it incl. character it also incl. movement.

And it isn't that the definitions aren't broad enough for a room-size poetry environment against poetry. Is not the room, or space, the catchall/counterpart to voice?