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(groff)Measurements

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Measurements
============

   `gtroff' (like many other programs) requires numeric parameters to
specify various measurements.  Most numeric parameters(1) (Note:
Measurements-Footnote-1) may have a "measurement unit" attached.
These units are specified as a single character which immediately
follows the number or expression.  Each of these units are understood,
by `gtroff', to be a multiple of its "basic unit".  So, whenever a
different measurement unit is specified `gtroff' converts this into its
"basic units".  This basic unit, represented by a `u', is a device
dependent measurement which is quite small, ranging from 1/75th to
1/72000th of an inch.  The values may be given as fractional numbers;
however, fractional basic units are always rounded to integers.

   Some of the measurement units are completely independent of any of
the current settings (e.g. type size) of `gtroff'.

`i'
     Inches.  An antiquated measurement unit still in use in certain
     backwards countries with incredibly low-cost computer equipment.
     One inch is equal to 2.54cm.

`c'
     Centimeters.  One centimeter is equal to 0.3937in.

`p'
     Points.  This is a typesetter's measurement used for measure type
     size.  It is 72 points to an inch.

`P'
     Pica.  Another typesetting measurement.  6 Picas to an inch (and
     12 points to a pica).

`s'
`z'
     Note: Fractional Type Sizes, for a discussion of these units.

   The other measurements understood by `gtroff' depend on settings
currently in effect in `gtroff'.  These are very useful for specifying
measurements which should look proper with any size of text.

`m'
     Ems.  This unit is equal to the current font size in points.  So
     called because it is _approximately_ the width of the letter `m'
     in the current font.

`n'
     Ens.  This is half of an em.

`v'
     Vertical space.  This is equivalent to the current line spacing.
     Note: Sizes, for more information about this.

`M'
     100ths of an em.

Default Units