Int 21 Fn FF0F  - Flu_shot+ V1.83 - Installation Check                     [v]

   AX = FF0Fh

Return: AX = 0101h if resident
Program: FLU_SHOT+ is an antivirus/antitrojan program by Ross M. Greenberg and
     Software Concepts Design

Note:  the "PSQR/1720" virus calls this function to determine whether
     FLU_SHOT+ is present

See Also: AH=FFh"VIRUS",AX=FF10h