heraldry language source?

[Joseph McMillan]

The compartment, as it is known, is not considered part of the armorial bearings unless it is specified in the letters patent in which the supporters are granted - which doesn't happen very often. It is usually just an artistic embellishment simply for the purpose of giving a place for the supporters to stand.

Since the secondary motto of MacMillan of Knap is "As long as the wave beats on the rock," I've always wanted someone to do a compartment with waves and rocks.

[MacMillan of Rathdown]

Since the secondary motto of MacMillan of Knap is "As long as the wave beats on the rock," I've always wanted someone to do a compartment with waves and rocks.

I seem to recall seeing something similar to what you propose (in one of the old "clan tartan" books?) with the supporters standing upon the rocks.