Rook and pawn hold against a queen when the king sits in the corner behind the pawn, the rook stands protected on the seventh rank, and every queen check can be met by a king or rook move that keeps the structure.
The queen chapter showed two rook-and-pawn fortresses; this one, in the corner, belongs to the same family often associated with Karstedt's analyses. Black's king on h8, rook on f7 and pawn on g6 protect each other: the king guards the rook's rank against the white king's approach, the pawn shields the king from diagonal checks, and the rook covers the seventh rank and the f-file.