Notice of MAPGEN/PLOTGEN Changes
						for Release 4

RELEASE 4 VS. 3

The main changes to the MAPGEN/PLOTGEN system relate to runline usage,
the nature of the MAPGEN definition file and the factor that four programs
have been removed from the system: *vector*, *pline*, *ppoint* and *plegend*.
Error monitoring has been improved and once elided errors in control streams
are much more likely to be complained about.  There are only one or two
changes (relating to infrequently used options) to the systems commands in
data streams so users should not have to do any conversion of existing input
data files.

The following gives a more detailed explanation of the changes and the user
should review the new *man* documentation.

DEFINITION FILE

The principle changes to MAPGEN's definition file are conversion from a
binary to an ASCII format and its approximation coefficients are now
determined by a quasi MINMAX method rather than least-squares.  As a
consequence, users must run the new MAPDEF program and replace previous
definition files.  Control input for the new MAPDEF program is the same as
the previous system except for the deletion of the autoscaling option
(using two geographic coordinates and inter-point distance).

Besides improving the mathematics, the purpose of the change was to make
the definition file fully system independent and transportable.  A definition
file made on an Ultrix machine is equally usable on a Sun or Data General.
The PLOTGEN definition also requires a minor modification of '#PLOTGEN:4' as
the first line of the file.

Overlays created with an older definition file made with the same MAPDEF
input script are fully compatible with the new system and do not require
regeneration.

RUNLINE CHANGES

Two major changes of runline parameters are the deletion of the '-i' switch
and the addition of the '-a' 'ov_file' option.  The latter option is the same
as the old '-o' 'ov_file' except that the output is appended to the file
'ov_file' rather than overwriting as in the case of '-o'.  If both '-o' and
'-a' are omitted, then output is to *stdout* and will cause a screen full of
funny characters if not properly redirected with the shell.

The '-m' is not required if the definition file is the first file on the
runline or the definition data precedes control information on the input stream.

Consistency of the overlay producing runlines has been improved.

THE .mapgenrc FILE

To help coordinate and customize frequently used operations with MAPGEN the
*.mapgenrc* system was installed.  Most of the system programs will search
the current directory for this file and if not present will search the
user's home directory.  When one is found, two entry lines in the file are
looked for that begin with "definefile:" and 'prog_name:' where 'prog_name'
is "lines", "points", ... .

The easiest way to describe this file is by looking at an example:

		definefile: /usr4/conmapA/con.def
		points: -sf - -ss .3 -s -cf - -cs .3 -cl 12
		lines: -sf - -cf - -ss .3 -sc .3
		legend: -f - -s .3 -l .5

The "definefile" line specifies the definition file to be used by the
overlay generating programs and the "points", "lines" and "legend" lines
allow the user to specify default settings of respective *points*, *lines*
and *legend* program parameters.  Note: a '#' in these control lines makes
the remainder of the line a comment.

When there is both a "definefile" line and an explicit runline '-m def_file'
specification, the runline file is used.  If a definition file is used first
on the runline without a '-m' and a *mapgenrc* file is used, it will be
treated as a data file and most likely cause error messages.

If there are lines with repeated \verb'definefile' or \verb'proj_name'
entries, only the first occurrence is used.

MAPGENINIT

The user may set an environment parameter MAPGENINIT with the name of a file
to be used instead of the *.mapgenrc* file.  For example:

		setenv MAPGENINIT ~/my_setup

for *csh(1)* users or

		MAPGENINIT /usr1c/jjones/my_setup
		export MAPGENINIT

for *sh(1)* users.

PROGRAM CONSOLIDATION

The old *plotgen* programs *ppoint*, *pline* and *plegend* have been merged
into respective programs *points*, *lines* and *legend*.  Unique features of
*vector* have been merged into program *lines*.  The only overlay generating
programs which remain unique to either subsystem are *coast*, *grid* and
*pgrid* and they will complain bitterly if the wrong type of definition file
is given.

Each of the programs can determine the nature of the data during processing
of the definition file.

XZOOM

Release 2.00 of *xzoom* is required for displaying overlay files when using
*mapgen* Rel. 4 definition files.

GRAPHICS PROGRAM

Release 4.4 or later of program *plotter* is required as well as linkage
with Rel. 4.4 of *libgraph.a* when installing the system.

PROJECTION PROGRAM

Release 3.0 or later of program *proj* is required.

DISTRIBUTION FILES

The following current distribution files for the complete system are located
in ``anonymous'' ftp/pub directory on charon.er.usgs.gov:

		proj-3.1.2.tar.Z
		graphics-4.5.tar.Z
		mapgen-4.1.tar.Z
		xzoom-2.0.tar.Z

PROBLEMS---QUESTIONS

If there are any problems or questions please call Gerald I. Evenden at
(FTS)837--4335 or (508)457-2335 or, better yet, send email to
gie@charon.er.usgs.gov .

If any bugs are detected, PLEASE inform me as soon as possible!