Originally Posted by ficbot
If I have a file which looks good in Sigil and I save it as epub, is it a clean file? Can I replace my buggy HTML master with it and use it forever like a commercial epub book (all of my commercial epub books have converted just fine to mobi). Is the epub code it generates cleaner than plain old HTML and I can be assured that things like em-dashes or curly quotes I might have forgotten to manually edit out will appear and be fine forever after?
Sigil will preserve your HTML to the best of its abilities. Usually it's pretty good.
It will convert it all to Unicode; if the file has em-dashes, curly quotes or other special characters, they will be preserved. But if there were problems with them in the original file, the problems will remain after it's processed by Sigil. There's no free lunch.
But if it all worked before, it should all work in Sigil too. Sigil being WYSIWYG, if there are any problems, you'll see them in the Book View. If it looks good in Sigil, your probably quite safe.