This call requests I/O privilege for disabling and enabling interrupts. Access to ports must be granted with DosPortAccess.
DosCLIAccess
rc (USHORT) - return
Applications that only use CLI/STI in IOPL segments must request CLI/STI privilege from the operating system.
Applications that use IN/OUT instructions to I/O ports must request I/O privilege with DosPortAccess. (See DosPortAccess for more detail.) Request for port access also grants CLI/STI privilege from the operating system.