The SEF Reader enables you to view SEF (Standard Exchange Format) files in a more readable format similar to that of most implementation guidelines. It supports SEF files for EDI X12 and UN/EDIFACT standards. It is free software. SEF or Standard Exchange Format is an open-standard, machine readable format file that defines the implementation guideline of a trading partner. The purpose of SEF is to standardize the format of implementation guidelines so that computers can obtain instructions (to process EDI files) from SEF files automatically.