+By default the @code{measureLength} and @code{beatLength} are
+derived from the time signature set by the @code{\time} command.
+The @code{measureLength} is set to be exactly the same length as
+the measure length given by the time signature, and the
+@code{beatLength} is set to be the same as one over the denominator
+of the time signature.
+
+The default value of @code{beatGrouping} is taken from a table in
+@file{scm/@/music@/-functions@/.scm}. To find this, see
+@rlearning{Other sources of information}. It defines the beat
+grouping for 5/8, 6/8, 8/8, 9/8 and 12/8 time signatures.
+
+Both @code{measureLength} and @code{beatLength} are @i{moments},
+units of musical duration. A quantity of type @i{moment} is
+created by the scheme function @code{ly:make-moment}. For more
+information about this function, see @ref{Time administration}.
+
+@code{beatGrouping} is a list of integers giving the number of
+beats in each group.
+
+@snippets
+
+@lilypondfile[verbatim,lilyquote,ragged-right,texidoc,doctitle]
+{grouping-beats.ly}
+
+@lilypondfile[verbatim,lilyquote,ragged-right,texidoc,doctitle]
+{specifying-context-with-beatgrouping.ly}
+
+@lilypondfile[verbatim,lilyquote,ragged-right,texidoc,doctitle]
+{using-beatlength-and-beatgrouping.ly}
+
+@funindex subdivideBeams
+
+@lilypondfile[verbatim,lilyquote,ragged-right,texidoc,doctitle]
+{sub-dividing-beams.ly}
+
+@cindex measure groupings
+@cindex beats, grouping
+@cindex grouping beats
+@cindex measure sub-grouping
+
+@lilypondfile[verbatim,lilyquote,ragged-right,texidoc,doctitle]
+{conducting-signs,-measure-grouping-signs.ly}
+
+
+@strong{@i{Modifying the beam end points}}
+
+In common time signatures, automatic beams can start on any note
+but can end at only a few positions within the measure, namely at
+durations specified by the properties in @code{autoBeamSettings}.
+These properties consist of a list of rules defining where beams can
+end. The default @code{autoBeamSettings} rules are defined in
+@file{scm/@/auto@/-beam@/.scm}. To find this, see
+@rlearning{Other sources of information}.
+
+This method @strong{must} be used for the time signatures for which
+beam-ending rules are defined by default, unless these have all
+been reverted. It is also particularly suitable for many other time
+signatures if the time signature of the measures changes frequently,
+or if the beaming should be different for different beam durations.