Xgremlin is a hardware and operating system independent version of the
data analysis program Gremlin for Fourier transform spectrometry.
Xgremlin runs on PCs and workstations that use the X11 window
system, including cygwin in Windows.  In Xgremlin few things have 
changed from Gremlin and someone familiar with Gremlin should 
immediately be able to work with Xgremlin.

Gremlin has two main input modes, an edit mode where commands
are entered at a command prompt and a graphical plot mode with
a different set of commands.  Xgremlin emulates these two input modes
by splitting the application main window into an upper pane which is
used for plotting and a lower pane used for command editing and
program output. Both windows remain visible all the time. After
startup Xgremlin is in edit mode and commands may be typed in at the
command prompt. To change over to plot mode either the button labeled
Plotmode or the Tab key must be pressed. Pressing either
of these again returns Xgremlin to 'edit' mode. The Xgremlin commands
in plot and edit mode are identical to those of Gremlin ( with a few
exceptions - the use of the Tab key being one of them ).

Xgremlin startup
----------------
One area where Xgremlin differs from Gremlin significantly is
initialization.  When Xgremlin is started it first reads a system wide
initialization file xgremlin.conf. The system wide initialization
file is used to establish defaults that are applicable to any user on
a system such as the printer that is to be used for screen
dumps. Xgremlin then processes the personal initialization file
.xgremlinrc in the home directory.  The personal initialization file
can be used to taylor Xgremlin to the liking of each individual user
e.g. to associate certain commands with buttons or to modify the colors
used in the plotting window.

GUI elements 
------------
In Xgremlin, frequently used commands can be accessed conveniently
through simple mouse clicks on buttons. All important plot mode
commands for moving around in a plot are accessible through the row of
buttons on top of the plotting window. Whereas the functions of the
top row of buttons are fixed, Xgremlin has also a row of buttons
between the plot and the edit window which may be programmed by the
user with the button command. This provides a convenient
shortcut for frequently used plot or edit commands. A online help
system can be called up by selecting the menu entry Help in the
Gremlins menu. The menu entry Phase/Tranform pops up an
interface to phase correction and Fourier transforms. This is
explained in greater detail in the Xgremlin tutorial.


Command line editing
--------------------
Xgremlin has a simple command line editor for the text window. 
The editor commands are reminiscent of those used in the much loved and
hated Unix editor Emacs:

 Left arrow key
 Move cursor to the left
 Right arrow key
 Move cursor to the right
 Page Up key
 Scroll text in edit window back by one page
 Page down key
 Scroll text in edit window forward by one page
 Up arrow key
 Recall previous command or commands
 Conrol key + 'a' key
 Move cursor to beginning of the command line (Anfang)
 Control key + 'e' key
 Move cursor to end of the command line (Ende)
 Control key + 'k' key
 Delete everything from cursor position to end of line
 Backspace key
 Remove character to left of cursor

Line lists
----------
Binary line list (.lin) files are supported by Xgremlin independent of
the computer type Xgremlin is running on. A line list file written on
a PC with an Intel processor is readable on a Sun workstation and vice 
versa. In more technical terms: the byte order of data in .lin files
is always identical to the byte order of data in .lin files produced
by the original Gremlin program (i.e. little endian byte order).

Documentation
-------------

All of the documentation is available in html format in the file
README.html.