What module handles word+period within paragraph fill?

Question

I'm experienced with elisp, and I'm using emacs 24.5.

I want to modify how fill-paragraph works for a special application, and I'm trying to figure out which elisp code handles the case where a short word followed by a period always goes to the next line.

For example, assume that some text looks like this:

Period at the end. And then blahblahblah and additional blahblahblah.

This text gets filled as follows (assume fill-column is 30):

Period at the
end. And then blahblahblah and
additional blahblahblah.

Note that the word "end" gets moved to the next line, even though the text length hasn't reached the fill-column value.

I'm trying to find the elisp code that handles this, so I can write my own version of this which overrides this behavior. I want the result to look like this:

Period at the end. And then
blahblahblah and additional
blahblahblah.

Could anyone point me to the 24.5 elisp code which handles this case?

Thank you very much.

Answer 1

What you are looking at is called sentence-end-double-space.

There is quite a bit of flexibility there, so I will not rehash the manual here.