@ESS{[BUGS]} was originally designed for use with BUGS software.  
Later, it evolved to support JAGS as a dialect of the
BUGS language via @ESS{[JAGS]}.  Since BUGS and JAGS are quite
similar, @ESS{[BUGS]} and @ESS{[JAGS]} are necessarily similar.
@ESS{[JAGS]} provides 4 features.  First, JAGS syntax is described to
allow for proper fontification of statements, distributions,
functions, commands and comments in JAGS model files, command files
and log files.  Second, @ESS{} creates templates for the command file
from the model file so that a JAGS batch process can be defined by a
single file.  Third, @ESS{} provides a JAGS batch script that allows @ESS{}
to set JAGS batch parameters.  Fourth, key sequences are defined to
create a command file and submit a JAGS batch process. 

@comment  node-name,  next,  previous,  up
@node ESS(JAGS)--Model files, ESS(JAGS)--Command files, ESS for JAGS, ESS for JAGS
@section ESS[JAGS]--Model files

Model files with the @file{.bug} extension are edited in @ESS{[BUGS]} mode
if @code{(require 'essd-bugs)} was performed or edited in @ESS{[JAGS]} mode
if @code{(require 'essd-jags)}.
Three keys are bound for your use in @ESS{[BUGS]}, @kbd{F2}, @kbd{C-c C-c} and @kbd{=}.
@kbd{F2} performs the same action as it does in @ESS{[SAS]},
@xref{ESS(SAS)--Function keys for batch processing}.  @kbd{C-c C-c} performs the
function @code{ess-bugs-next-action} which you will use a lot.  Pressing it
in an empty buffer for a model file will produce a template for you.  @kbd{=}
inserts the set operator, @code{<-}.

@ESS{[JAGS]} does not support "replacement" variables which were part of
@ESS{[BUGS]}.  Although, "replacement" variables are an extremely convenient
feature, creating the elisp code for their operation was challenging.  So, a
more elisp-ish approach was adopted for @ESS{[JAGS]}:  elisp local variables.
These variables are
created as part of the template, i.e. with the first press of @kbd{C-c C-c} 
in an empty buffer.  For your @file{.bug} file, they are named 
@code{ess-jags-chains}, @code{ess-jags-monitor}, @code{ess-jags-thin},  
@code{ess-jags-burnin} and @code{ess-jags-update};
they appear in the @code{Local Variables} section.  When you are
finished editing your model file, pressing @kbd{C-c C-c} will perform
the necessary actions to build your command file for you. 

The @code{ess-jags-chains} variable is the number of chains that
you want to initialize and sample from; defaults to 1.
The @code{ess-jags-monitor} variable is a list of variables
that you want monitored: encase each variable in double quotes.  
When you press @kbd{C-c C-c}, the
appropriate statements are created in the command file to monitor the
list of variables.  By default, no variables are explicitly monitored 
which means JAGS will implicitly monitor all ``default'' variables. 
The @code{ess-jags-thin} variable is the thinning parameter.  
By default, the thinning parameter is set to 1, i.e. no thinning. 
The @code{ess-jags-burnin} variable is the number of initial samples
to discard.  By default, the burnin parameter is set to 10000.
The @code{ess-jags-update} variable is the number of post-burnin samples
to keep.  By default, the update parameter is set to 10000.  Both 
@code{ess-jags-burnin} and @code{ess-jags-update} are multiplied by
@code{ess-jags-thin} since JAGS does not do it automatically.

@comment  node-name,  next,  previous,  up
@node ESS(JAGS)--Command files, ESS(JAGS)--Log files, ESS(JAGS)--Model files, ESS for JAGS
@section ESS[JAGS]--Command files

To avoid extension name collision, @file{.bmd} is used for BUGS
command files and @file{.jmd} for JAGS command files.  For your 
@file{.jmd} file, there is only one variable, @code{ess-jags-command}, 
in the @code{Local Variables} section.  When you have
finished editing your model file and press @kbd{C-c C-c}, a command
file is created if one does not already exist.  
When you are finished editing your command file, pressing @kbd{C-c C-c} 
again will submit your command file as a batch job. 
The @code{ess-jags-command} variable allows you to specify a different
JAGS program to use to run your model; defaults to ``jags''.

@comment  node-name,  next,  previous,  up
@node ESS(JAGS)--Log files, , ESS(JAGS)--Command files, ESS for JAGS
@section ESS[JAGS]--Log files

The @file{.jog} extension is used for JAGS log
files.  You may find @kbd{F2} useful to refresh the @file{.jog} if the batch
process over-writes or appends it.