



In practice, you often have good reasons for editing "finished" print files – whether to add minor corrections, replace individual characters, remove short sections of text, or add annotations. Editing PDF files therefore contradicts the stated aim of the file format: unchanged forwarding. It is based on the PostScript programming language, a PDF being a compiled – and thus no longer editable – version of the PostScript code. PDF was originally designed as a print format for forwarding and exchanging documents without allowing changes.
