Subject: bug#19873: Ill-formed regular expression is constructed in forward-paragraph.

From: Eli Zaretskii <[email-masked]>
Date: Sun, 26 Feb 2017 18:57:05 +0200

> From: Marcin Borkowski <[email-masked]>
> Date: Sun, 26 Feb 2017 17:44:51 +0100
> Cc: [email-masked]
> 
> First of all, my Emacs has this as paragraph-start:
> 
> "\\|[ 	]*$"
> 
> and this as paragraph-separate:
> 
> "[ 	]*$"
> 
> and frankly speaking, I'm not sure why they differ at all (by default).

I believe this is explained in the Emacs manual, node "Paragraphs".
In a nutshell, these two regexps have different purposes.