E2P files are associated with serial device programmer PonyProg, available for Windows systems. E2P files contain information about devices that can be programmed using PonyProg GUI.

A characteristic feature of E2P file is the ASCII string "E2P! Lanc" or HEX code 45 32 50 21 4C 61 6E 63 at the beginning of the file. PonyProg was developed for older Microsoft Windows (95 to XP) and Linux systems. Using E2P files on newer systems might result in compatibility problems.