Int 48 Fn 1A70  U - Compaq Uilib.exe - Installation Check                  [V]

   AX = 1A70h
   BX = call type (see below)

Return: CX = 5649h ('VI') if installed
   DX = 4557h ('EW') if installed
       AX = version??? (0106h)

Values for call type:
 0000h near
 0001h far
 0002h INT (only valid call type when using INT 48)
 0003h near