Originally Posted by A Lurker
On its own, Calibre is removing my tabs and inserting spaces between paragraphs. That's the underlying problem. There is nothing self-inflicted about it. My question is: How do I get Calibre to stop doing reformatting my document on its own?
The problem is that in the HTML based formats used by eBooks such as ePub and mobi tabs have no effect at all on formatting. It makes no difference whether Calibre removes them or leaves them - it does not affect the output formatting. Therefore you cannot use tabs to control formatting - you have to use some other mechanism such as styles.