Key mapping in x5250 is accomplished using X resources just like every other
customizable feature.  And just like every other resource key maps can be
specified at a system level as well as a user level.  The system level
resources are stored in $PREFIX/share/x5250/X5250 where $PREFIX is what you
specified in the --prefix option in ./configure (if you didn't specify
anything this defaults to /usr/local).  The user level resources are in
$HOME/.Xdefaults (where $HOME is your home directory).

The key map resources all have a similar form.  An example of the enter key
resource is below:

X5250*Enterkey			: 0xFF0D

All key map resources are named <key>key where <key> is the name of the key
you want to override.  The rules for capitalization of resource names are
defined by X11 and are outside the scope of this document.  Suffice it to
say that capitalized names denote classes and lower case name denote specific
instances.  See your X11 documentation for more info.

Key map resource values consist of hex keysyms.  The keysyms are not
generally portable across different platforms.  However, it is simple to find
out what keysym corresponds to a given key by using the 'xev' program included
in your X11 distribution.  For example, to find out what keysym corresponds
to the right control key start xev from a terminal and press the right control
key.  On the terminal you will see something similar to the following output:

KeyPress event, serial 24, synthetic NO, window 0x2000001,
    root 0x5d, subw 0x0, time 68254049, (92,58), root:(1887,82),
    state 0x0, keycode 109 (keysym 0xffe4, Control_R), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

The important values here are "state 0x0" and "keycode 109 (keysym 0xffe4,
Control_R)".  The state indicates what other modifier keys were being held at
same time as this key was pressed.  The keysym value is 0xffe4 which is what
we are interested in.  Thus to map the 'enter' key to be the right control
key we would set the following resource:

X5250*Enterkey			: 0xFFE4

This will make all instances of x5250 use the right control key as 'enter'.

You can also make key maps that use key combinations.  Key combination maps
are enclosed in parentheses and are of the form (<state> <keysym>).  Again you
use xev to find out what values to use for state and keysym.  For example,
suppose you wanted to map shift+enter to field exit.  Using xev, press shift
and enter together and look on your terminal for a line similar to the
following:

KeyPress event, serial 27, synthetic NO, window 0x2000001,
    root 0x5d, subw 0x0, time 68963306, (102,113), root:(1897,137),
    state 0x1, keycode 36 (keysym 0xff0d, Return), same_screen YES,
"   XLookupString gives 1 bytes: (0d) "
"   XmbLookupString gives 1 bytes: (0d) "
    XFilterEvent returns: False

This time the value of state is 0x1 and the keysym value is 0xff0d.  So the
correct resource for this is:

X5250*Fieldexitkey			: (0x1 0xFF0D)

State values can be listed separately, though xev doesn't do so.  On my
system, the state value for shift is 0x1 and the state value for control is
0x4.  Pressing both of these together in xev will result in a state value of
0x5.  Thus for shift+ctrl+enter you could use either (0x1 0x4 0xFF0D) or
(0x5 0xFF0D).

You can also make multiple maps for the same key.  Maps are separated by
spaces.  If you wanted to make both the return key and the 10-key enter key
map to field exit, you would use the following resource:

X5250*Fieldexitkey			: 0xFF0D 0xFF8D

Of course, use xev to verify that the above keysyms are correct for your
system.

Multiple key maps using key combinations are also supported.  There is no
limit to the number of key maps you can specify.

For a complete list of keys which can be mapped and their resource names
please the file X5250 included in the x5250 distribution.

Finally, keep in mind that keymap resources are in addition to the x5250
default key maps, not in place of.  Thus if you map 'enter' to right control
the default of return (or the 'real' enter key) is still active.  The X5250
resource file lists the current default key maps.


Addtional notes:

Resource files use the ! character to indicate a comment.  Any line beginning
with ! will be ignored.  The X5250 resource file included in the x5250
distribution has all the key map resources commented (because they are coded
into x5250 itself).  Be sure to remove the ! from the beginning of the line
to make your resources effective.

The state field in xev will show all modifier keys that are currently active,
including some that you may not think of as modifier keys.  For example, the
NumLock key is a modifier key.  On my system, if the NumLock key is active
the state field will show 0x10 with no other modifier keys pressed.  Be sure
that the state field doesn't have something you don't expect (i.e. unset all
modifier keys when using xev).  x5250 ignores the state of NumLock and
CapsLock when checking the current key states, but can't determine if you have
included them in the state field of your maps.  Therefore, if you include
either of these keys in the state field of your maps x5250 won't be able to
match them.