Info Catalog groff: Text groff: gtroff Reference groff: Expressions

groff: Measurements

 
 5.2 Measurements
 ================
 
 'gtroff' (like many other programs) requires numeric parameters to
 specify various measurements.  Most numeric parameters(1) (⇒
 Measurements-Footnote-1) may have a "measurement unit" attached.
 These units are specified as a single character that 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'.
 
    Although groff's basic unit is device-dependent, it may still be
 smaller than the smallest unit the device is capable of producing.  The
 register '.H' specifies how many groff basic units constitute the
 current device's basic unit horizontally, and the register '.V'
 specifies this value vertically.
 
 'i'
      Inches.  An antiquated measurement unit still in use in certain
      backwards countries with incredibly low-cost computer equipment.
      One inch is defined to be 2.54 cm (worldwide since 1964).
 
 'c'
      Centimeters.  One centimeter is about 0.3937 in.
 
 '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'
      ⇒Fractional Type Sizes, for a discussion of these units.
 
 'f'
      Fractions.  Value is 65536.  ⇒Colors, for usage.
 
    The other measurements understood by 'gtroff' depend on settings
 currently in effect in 'gtroff'.  These are very useful for specifying
 measurements that 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.  In 'groff', this is half of an em.
 
 'v'
      Vertical space.  This is equivalent to the current line spacing.
      ⇒Sizes, for more information about this.
 
 'M'
      100ths of an em.
 

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Info Catalog groff: Text groff: gtroff Reference groff: Expressions