File: groff.info,  Node: Traps,  Next: Diversions,  Prev: Deferring Output,  Up: GNU troff Reference

5.28 Traps
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"Traps" are locations in the output or conditions on the input that,
when reached or fulfilled, call a specified macro.  These traps can
occur at a given location on the page, at a given location in the
current diversion (together, these are known as vertical position
traps), at a blank line, at a line with leading space characters, after
a quantity of input lines, or at the end of input.  Macros called by
traps are passed no arguments.  Setting a trap is also called "planting"
one.  It is said that a trap is "sprung" if its condition is fulfilled.

* Menu:

* Vertical Position Traps::
* Diversion Traps::
* Input Line Traps::
* Blank Line Traps::
* Leading Space Traps::
* End-of-input Traps::