1) System management interrupt 
See Supplemental Medical Insurance.
System Management Interrupt (SMI) - Similar to NMI, except it is used specifically to handle power management and system management issues. The interrupt handler for a SMI runs from a protected memory space (SMRAM), so the OS has no access to this handler code. SMI is primarily used for ACPI and APM support.
System Management Interrupt [Intel]
Structure of Management Information.