The Portable Document Format (PDF) is a proprietary document format from Adobe Inc. It is widely available on the web.
Each file begins with the string %PDF. Each block ends with the letters EOF, but there can be multiple EOF's in a single file (this often confuses programs like foremost that search for footers).
- Adobe PDF Reference
- Wikipedia: PDF
- Portable Document Format: An Introduction for Programmers, MacTech Magazine, Volume 15, (1999), Issue 9