Hello Benno, thanks for your quick reply.
On Sun, Jul 12, 2020 at 13:15:41 +0200, Benno Schulenberg wrote: > Ideally, a UTF-8 file should not contain a Byte Order Mark. What if > I concatenate several files together? Then the result might contain > BOMs embedded in the text. > > As far as I know, BOM is only a problem with Windows and Google files. > I do not know of any tool on Unix that adds a BOM to a UTF-8 file. I agree, that a UTF8-BOM is usually not necessary. Probably because of the mentioned compatibility reasons on Windows 'aegisub' does always include a BOM when saving as UTF-8 (concatenating two valid ASS files wouldn't produce a new valid ASS file anyway). > […] And the Unicode standard > does not forbid the BOM from occurring elsewhere -- in that case > it should be considered as a Zero Width Non Breaking Space. Thanks for pointing it out, I wasn't aware of this. In that case it is probably just good practice(?) to have a BOM only at the beginning. > I could mitigate the problem by placing the cursor after the BOM > when a file is opened. (See attached patch.) But you can still > delete the BOM with <Backspace>, or put the cursor on it with > <Left> or <Home>. For nano, all characters are just a group of > bytes that can be added, deleted, restored, searched, and saved. > > If I would make the BOM uneditable and unmovable, people could > no longer use nano to get rid of a BOM in a file. > > https://bugs.launchpad.net/ubuntu/+source/nano/+bug/1045062 With the explanation having nano's current behaviour seems like a valid approach, though there's a chance a user, who isn't aware of it, might move or delete the BOM by accident. The patch would make this less likely (but it would still be possible). FWIW I would have expected leading BOM/NoBOM to be an option when saving with ^O (like DOS/Mac-Format) and by default keep status quo. (looking at other editors, vim has this as :set bomb / :set nobomb ). Or for the BOM to be visible. Though being visible would contradict the interpretation as a zero-width-nb-space, so maybe not. Nils
