This type is not a standard SMI/SNMP base type and is not defined as a documented TEXTUAL-CONVENTION in this MIB.
It was extracted as raw syntax from the source MIB file and could not be resolved to a known type definition.
The local autonomous system (AS) number.
RFC 4271, Section 4.2, 'My Autonomous System'. RFC 4893, BGP Support for Four-octet AS Number Space.