> Why anyone treats PDF as anything but a write-once format is beyond me. Because PDF is supposed to be like electronic paper and you normally can draw on a pa

> Why anyone treats PDF as anything but a write-once format is beyond me. Because PDF is supposed to be like electronic paper and you normally can draw on a paper original. In an ideal world OSes and apps would be better equipped to separate data and metadata and work with multi-stream files. Every file would have different kinds of pure data (e.g. scanned picture and OCRed text), metadata (e.g. title, author, ISBN/etc IDs, ToC etc) and user-generated annotations in separate streams. But our actual world is not ideal, we mix everything into one stream for every document and allow the apps modify it every time we view it.