RFC
distinct version of an Internet standards-related specification
NOTE See RFC 2026.
IG
data specification that is in the syntax specified in ISO/TS 22745-30 and that uses concept identifiers from an open technical dictionary
NOTE 1 An identification guide is typically maintained by an organization that receives data, e.g., a buyer or group of buyers.
NOTE 2 An identification guide is sometimes referred to as a "template of properties and rules".