Maybe the wiki value has a more understandable description than the readme?
http://dosbox.sourceforge.net/wiki/index.php?page=KeyMapper

[edit]
N/M, Just looked at the mapper section of the readme and it's very detailed. Much more than the wiki page...

Well, I've read the 'README.txt' and the corresponding section in the wiki several times, but I am still unclear.

I mean: I want to send a '#' to the game, so I open the keymapper and click on '3#', but DosBox shows 'key_3' as Event. But I want to use '#' as Event.

And I want to change 'Ctrl + F11' for 'Ctrl + 0', not 'F11' for '0' (where I know how to proceed).

Thanks in advance.
Matt.

You can only remap keys, not characters. Maybe re-read the whole section
of the readme to get an idea of it, as Og said.
If you want ctrl-0 to behave like ctrl-f11, click on the f11 in the mapper,
click add, then hit the 0-key on your keyboard.

The mod1,2,3 and hold are not explained well in the readme.txt file.

How would I get the physical Shift-3 key combination to be the Event key_f3?
That is, map the keyboard Shift-3 to be an F3 (no shift) sent to the application?

You can't. As stated several times the mapper remaps only keys to keys.
The mod keys are for special functionality.

wd wrote:

If you want ctrl-0 to behave like ctrl-f11, click on the f11 in the mapper,
click add, then hit the 0-key on your keyboard.

But now I need to type the number 200 in the game, for example. I press '2', then '0' ... wouldn't I be sending '2' and 'F11' to the game. Because this way I have mapped '0' as 'F11', not 'Ctrl + 0' as 'Ctrl + F11'.

And how could I do to send the '#' character to the game.

By the way, the game I am talking about is VPA (VGA Planets Assistant, vpa.sourceforge.net).

Thanks.

But now I need to type the number 200 in the game

Well then your initial choice of kicking the 0 key was quite bad, right?
I'm sure you'll find some key that isn't used. If not, search harder.

And how could I do to send the '#' character to the game.

That's a completely different thing, again the mapper is for KEYS not
for characters.
I don't see any problem with pressing shift-3 (us layout) to generate that
character. If you want a different layout, look at the keyboardlayout section
of the readme.