@Chapter
   @Title { Principles }
   @Tag { principles }
@Begin
@LP
The Lout document formatting language is based on just four key ideas:
objects, definitions, cross references, and galleys.  This chapter
concentrates on them, postponing the inevitable details.
@BeginSections
@Include { pri_obje }
@Include { pri_defi }
@Include { pri_cros }
@Include { pri_gall }
@EndSections
@End @Chapter