14.1. Feature Description 
The Multi-Level Precedence and Preemption (MLPP) service provides
prioritized call handling service. This service has two parts - Precedence
and Preemption.
The specific requirements for MLPP are described in the Generic Switching
Center Requirements (GSCR) document (September 8, 2003). The GSCR specifies
support for different types of switches. This document focuses on PBX1
and SMEO (Small Enterprise Office).
Precedence
Precedence involves assigning a priority level to a call.
Preemption
Preemption involves a higher precedence call seizing resources
that are in use by a lower precedence call, in the absence of idle resources.