INT 2F U - DOS 4+ XMA2EMS.SYS extension internal - GET HIDDEN FRAME INFORMATION
AH = 1Bh
AL <> 00h
DI = hidden physical page number
Return: AX = FFFFh if failed (no such hidden page)
AX = 0000h if OK, then
ES = segment of page frame
DI = physical page number
Notes:  this corresponds to the data edited out of the INT 67/AH=58h call
FASTOPEN makes this call with AL = FFh

See also: 2F1B00

2F1B - DOS 4+ XMA2EMS.SYS extension internal - GET HIDDEN FRAME INFORMATION