.IH "1	INTRODUCTION"
\fBBackground\fR
.sp 1.5
This reference manual details the use of programs distributed with
version 5.0 of the Geographical Resources Analysis Support System 
(GRASS), a public domain, image processing and geographic information
system (GIS).  The GRASS system is used to input, manipulate, 
analyze, and output geographic data by users in both military and 
non-military, public and private agencies based in North America, 
Europe, and other parts of the world.
.sp 
Although most GRASS development has been conducted at USACERL, system
integration, development, testing, distribution, training, and
support are performed by numerous publicly and privately operated
sites throughout the world. 
.sp 2
\fBReference Manual\fR
.sp 1.5
The manual explains the capabilities, syntax, and use of current
GRASS programs.  Chapters 
contain program entries which are ordered alphabetically by program name.
Each entry contains:
.sp
	*  the program name 
.br
	*  a brief description
.br
	*  a synopsis of files associated with the program
.br
	*  a full description of the program's capabilities and uses
.br
	*  a summary of the command-line operations associated with the program
.br
	*  a list of associated or related programs
.br
	*  a list of program authors
.sp 
Each entry may optionally include a description of the program's operation
in interactive mode, and a discussion of "bugs," program limitations, or special notes of interest.
.sp
Throughout the manual, program input to be explicitly entered by
the user is printed in bold text.  User-specified input (i.e., variables
set by the user) is set in italic type.  Boxed text shows information
output to the user's terminal screen.
.sp 2
\fBGRASS Categories\fR
.sp 1.5
The GRASS code has been divided into the following categories according
to reliability, testing, and application:
.sp 2
	*  Main and Alpha
.br
	*  UNIX Shell Scripts
.br
	*  Contributed
.br
	*  Garden
.br	
	*  Related
.KE
.sp
Descriptions of Main and Alpha, Shell Script, and Contributed
categories are presented at the introduction of
each appropriate chapter in this manual.

Other software distributed
with GRASS but not documented in this manual includes:

(1)	Hardware- and software-specific code:  SG3d (specific to Silicon Graphics computers) and XGRASS 
(specific to 
\fIMotif\fR).

(2)	Garden and 
Related programs contained in the
.I src.garden
and
.I src.related 
directories, which the user must compile separately (see the
GRASS \fIInstallation Guide\fR for compilation instructions):  
Any original documentation for these programs is compiled on-line with the
directories.  Garden includes program interfaces that link GRASS 4.1
with other related software.  Related includes programs to which GRASS has been
interfaced and that program developers have allowed to be distributed
with GRASS.