[queuebert]

PDFs are essentially compressed Postscript, which is Turing complete, so a PDF in theory can do anything you want.

[tonyedgecombe]

The big distinction between PostScript and PDF was the removal of the language operators[1]. Adobe Distiller unrolled the PostScript language to create a file without the code.

[1] A small part remained for defining calculations as well as support for PostScript fonts.