File: groff.info,  Node: Breaking,  Next: Adjustment,  Prev: Hyphenation,  Up: Text

5.1.4 Breaking
--------------

Once an output line is full, the next word (or remainder of a hyphenated
one) is placed on a different output line; this is called a "break".  In
this manual and in 'roff' discussions generally, a "break" if not
further qualified always refers to the termination of an output line.
When the formatter is filling text, it introduces breaks automatically
to keep output lines from exceeding the configured line length.  After
an automatic break, GNU 'troff' adjusts the line if applicable (see
below), and then resumes collecting and filling text on the next output
line.

   Sometimes, a line cannot be broken automatically.  This usually does
not happen with natural language text unless the output line length has
been manipulated to be extremely short, but it can with specialized text
like program source code.  We can use 'perl' at the shell prompt to
contrive an example of failure to break the line.  We also employ the
'-z' option to suppress normal output.

     $ perl -e 'print "#" x 80, "\n";' | nroff -z
         error-> warning: cannot break line

   The remedy for these cases is to tell GNU 'troff' where the line may
be broken without hyphens.  This is done with the non-printing break
point escape sequence '\:'; see *note Manipulating Hyphenation::.

   What if the document author wants to stop filling lines temporarily,
for instance to start a new paragraph?  There are several solutions.  A
blank input line not only causes a break, but by default it also outputs
a one-line vertical space (effectively a blank output line).  This
behavior can be modified; see *note Blank Line Traps::.  Macro packages
may discourage or disable the blank line method of paragraphing in favor
of their own macros.

   A line that begins with one or more spaces causes a break.  The
spaces are output at the beginning of the next line without being
_adjusted_ (see below); however, this behavior can be modified (*note
Leading Space Traps::).  Again, macro packages may provide other methods
of producing indented paragraphs.  Trailing spaces on text lines are
discarded.(1)  (*note Breaking-Footnote-1::)

   What if the file ends before enough words have been collected to fill
an output line?  Or the output line is exactly full but not yet broken,
and there is no more input?  GNU 'troff' interprets the end of input as
a break.  Certain requests also cause breaks, implicitly or explicitly.
This is discussed in *note Manipulating Filling and Adjustment::.