The Structure of Management Information version 2 (SMIv2) is the data modeling language used to define managed objects accessible via SNMP operations and is published as IETF Internet Standard 58 in three RFCs as follow:

RFC 2578 Structure of Management Information Version 2 (SMIv2)

RFC 2579 Textual Conventions for SMIv2

RFC 2580 Conformance Statements for SMIv2