INT 2F U - DOS 3.3+ internal - MOVE FILE POINTER
AX = 1228h
BP = 4200h, 4201h, 4202h (see INT 21/AH=42h)
BX = file handle
CX:DX = offset in bytes
SS = DOS DS (must be using a DOS internal stack)
Return: as for INT 21/AH=42h
Notes:  equivalent to INT 21/AH=42h, but may only be called from inside a DOS
function call
sets user stack frame pointer to dummy buffer, moves BP to AX, performs
LSEEK, and restores frame pointer

See also: 2142

2F1228BP4200 - DOS 3.3+ internal - MOVE FILE POINTER