Left space-bar remapping question: scan codes, xkb and all that ...

[Diagon]

The basic question:

Guys, I know people remap their left space bar, sometimes to a backspace.  I'm trying to figure out how to remap it to something more flexible, basically an unused scan code that can then be mapped in software by xkb.  Only, now I'm stuck in a blizzard of USB Keyboard HID specs and xkb how-to's.  So what "scan code" should I map it to?  Is there a list somewhere of what I could use?  Ok, I found the list: https://www.scribd.com/doc/46294537/USB-HID-Translation-Code, where the "HID Usage ID" is, I assume, telling me the 16 bits that are output by the keyboard when that key is pressed.  So, my untutored mind says one of the F13-F24 might be the right choice (?)

Once that's solved ...

So then, I have ideas of using that space bar for another layer.  Can someone tell me if it's possible to use L-space as a shift, so that I can move numbers and symbols onto the home-row + the keys just above/below?  To make this convenient, I'd perhaps like to have single L-space be a dead key, double L-space be a shift lock, and the shift-lock would be cancelled by a later L-space.

Please let me know if I'm on target with this.  I'm using Linux, and I'd be doing it with a Freestyle Solo, by RMA'ing it to Kinesis where they'll do the remapping.  While I'm at it, I'll probably have them switch the Fn & Menu key.  If you have thoughts on what else I might consider, fire away!

Thanks for your input!
/DA

Goldtouch, Kinesis Maxim x2, Freestyle Solo x3, Advantage, and a TEK on the way! 
And ... all Linux, all the time.

[Pro XKB]

So, my untutored mind says one of the F13-F24 might be the right choice (?)

I do not know, but if you plan to make that key your left shift key, using the scancode for the left shift key might be an alternative.

To make this convenient, I'd perhaps like to have single L-space be a dead key, double L-space be a shift lock, and the shift-lock would be cancelled by a later L-space.

You can achieve this by mapping the keysym ISO_Level2_Latch to your key, and put Shift in the modmap of that key.  If you have selected the scancode for F13, it will look like this:

    key  <FK13> {
        type= "ONE_LEVEL",
        symbols[Group1]= [  ISO_Level2_Latch ]
    };
    modifier_map Shift { <FK13> };

[pyro]

I think most split-spacebar keyboards send the same keycode when you press either spacebar, so it might be impossible to remap just one half of it to something else, depending on your keyboard. Also, my Lubuntu came with the Neo layout preinstalled (file /usr/share/X11/xkb/symbols/de, search for "neo"), which makes extensive use of layers. You might be able to work from there.

Also, this
http://hack.org/mc/writings/xkb.html
and this
http://www.charvolant.org/~doug/xkb/html/node5.html
might be of interest to you, too.

[Oobly]

... I'd be doing it with a Freestyle Solo, by RMA'ing it to Kinesis where they'll do the remapping.  ...

How about you ask Kinesis about it? Another option for a scancode to map is the ISO key scancode (100). It's a standard keycode and supported on all systems, but the physical key is not present on ANSI layouts.

[natas206]

Please let me know if I'm on target with this.  I'm using Linux, and I'd be doing it with a Freestyle Solo, by RMA'ing it to Kinesis where they'll do the remapping.  While I'm at it, I'll probably have them switch the Fn & Menu key.  If you have thoughts on what else I might consider, fire away!

We can do this at Kinesis (left space = backspace). We cannot change the Fn key location or behavior however. It's hardwired.