The MIB module for managing SONET linear Automatic Protection Switching (APS) architectures. The objects defined in this MIB are based on the following industry references: 1. ANSI T1.105.01-1995, 'Synchronous Optical Network (SONET) - Automatic Protection Switching'. 2. Telcordia Technologies (Bellcore) GR-253-CORE, Issue 2, Revision 2 (January 1999), 'SONET Transport Systems: Common Criteria References' sections 5.3 and 6.2.1.1.6.