[Tex2002ans]

Originally Posted by jppeltier

For the sake of completeness and further reference to French rules, I found the following resources (albeit in French only) of particular interest:
https://crowdagger.github.io/textes/...uristique.html
https://www.druide.com/fr/enquetes/p...es-impeccables
https://roberge.mus.ulaval.ca/gdrm/08-princ.htm

Thanks for these resources. I'll toss them on my reading lists.

Here's another one to add to yours:

LibreOffice's article: "Non Breaking Spaces Before Punctuation In French (espaces insécables)"

Side Note: For all the different thin/normal spacing around punctuation... you have to know the specific language's conventions. Even within French, there are differences between French + Canadian French punctuation.

* * *

Over the years, I've written extensively on non-breaking spaces in ebooks. Here are some of the threads that go into extreme detail on non-breaking spaces (and other types of spaces):

2019 "ellipses, with or without spaces?"
2017 "break/no-break and other spaces"
2014 "Non-breaking space"
2013 "[old thread] non breaking spaces (* and &#x00A0 automatically removed"

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Questions: You seem to be an actual French speaker... how would French handle odd punctuation like question marks within brackets:

(?) or [?]

Do similar spacing rules apply for more obscure punctuation like {} + &?

Or what about Maths (+, −, =)? Do they follow normal conventions? Or apply some sort of insane French version of spacing? :P

Originally Posted by jppeltier

Hello, I am giving a first shot at creating an ePUB, and am struggling with non-breaking spaces.

Long story short, in French punctuation:

For maximum compatibility, use  ... NO-BREAK SPACE (U+00A0).

This is the solution you should use for ebooks. Other spaces are less supported and may lead to missing character symbol � showing up.

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Side Note: If creating French documents for Print:

For proper French typography, stick with these two:

•   or   = NO-BREAK SPACE (U+00A0)
•   or   = THIN SPACE (U+2009).
  
  • Many programs don't break on the THIN SPACE, so will keep punctuation attached. (Unsure on ereaders though, I haven't done extensive testing.)

To be super extra technically correct, the thin space would be a NARROW NO-BREAK SPACE (U+202F). But this character isn't in many fonts according to my tests.

For more details/tests of different fonts/applications, see my Post #48 in "Problem with inline image".

Originally Posted by RbnJrg

And how should the non-breaking spaces show? [...]

Well, in LibreOffice all the other spaces show as gray highlight, and in Calibre, it shows yellow highlight. :P

Originally Posted by DNSB

AFAIK, a non-breaking space does not have a fixed length so it will not have any effect on justification.

Correct...

But there are bugs, and some major programs that don't follow this logic... See all the juicy details in LibreOffice's bug:

Bug 41652 - "NO-BREAK SPACE" (U+00A0) interpreted as fixed-width space

In Word 2013, Microsoft finally stopped treating it as a fixed-width space:

https://answers.microsoft.com/en-us/...f06c7cb?auth=1

but... I believe they since reverted that (correct) decision in Word 2016+.