Most trading partners use the ANSI X.12 standards for EDI transactions. However, a few automotive trading partners may use EDIFAC standards. A subset of the ANSI X.12 standards, VICS, is used by many retailers. EDI standards specify segment and element names as well as usage for transaction types and envelope construction. Envelope construction is one aspect of EDI standards that is uniform for all trading partners, and envelopes are discussed in more detail on the following page. Still, there is flexibility within these EDI standards for each trading partner to construct transactions that meet their needs.