emacs: Hard and Soft Newlines

 
 25.14.2 Hard and Soft Newlines
 ------------------------------
 
 In Enriched mode, Emacs distinguishes between two different kinds of
 newlines, “hard” newlines and “soft” newlines.  You can also enable or
 disable this feature in other buffers, by typing ‘M-x
 use-hard-newlines’.
 
    Hard newlines are used to separate paragraphs, or anywhere there
 needs to be a line break regardless of how the text is filled; soft
 newlines are used for filling.  The <RET> (‘newline’) and ‘C-o’
 (‘open-line’) commands insert hard newlines.  The fill commands,
 including Auto Fill (SeeAuto Fill), insert only soft newlines and
 delete only soft newlines, leaving hard newlines alone.
 
    Thus, when editing with Enriched mode, you should not use <RET> or
 ‘C-o’ to break lines in the middle of filled paragraphs.  Use Auto Fill
 mode or explicit fill commands (SeeFill Commands) instead.  Use
 <RET> or ‘C-o’ where line breaks should always remain, such as in tables
 and lists.  For such lines, you may also want to set the justification
 style to ‘unfilled’ (SeeEnriched Justification).