Per Bend Sinister Rompu
Master layer
Layer 3
Equal field division. May use any two tinctures, except if overlain by a charge in which case must not be sable and purpure or sable and azure.
The only example I've found of this design is in the arms of Aleyn / Allen; if it is indeed the only such instance, it may not be registrable today.
Use with charges would be a Step From Core Practice (SFCP).
Source: Insignia Anglica. Artist unknown. (Arms of Aleyn, folio 33r.)