The same “dual path” approach as for PGF is used when saving EPS-compatible files in recent versions of Illustrator. pgf using the same name Progressive Graphics Format. PDF compatibility is achieved by embedding a complete copy of the PGF data within the saved PDF format file. The AI file format was originally a native format called PGF. ai filename extension is used by Adobe Illustrator. Adobe Illustrator Artwork ( AI) is a proprietary file format developed by Adobe Systems for representing single-page vector-based drawings in either the EPS or PDF formats.
