Ergonomic keys can be added by:

(ergoemacs-key "M-a" 'execute-extended-command "Execute")

This adds the Alt-a command to all keyboards based on the QWERTY layout. This only applies to the currently selected keyboard theme.

Note the last parameter is optional and allows Ergoemacs to document that this is an "Execute" command when generating keyboard layout diagrams.

Fixed keys can be added by:

(ergoemacs-fixed-key "C-o" 'ido-find-file "Open File")

This adds the fixed key to the currently selected emacs theme

Note the last parameter is optional and allows Ergoemacs to document that this is an "Open" command when generating keyboard layout diagrams.

When you want to add an ergonomic keymap with fixed mappings such as the ergoprog theme you can add them as follows:

(ergoemacs-key "M-m s" 'save-buffer "" t)

This converts the QWERTY M-m keybinding and the fixed keybinding s to save buffer

Ergoemacs respects emacs globally defined keys. To define a global key, you can use:

(global-set-key (kbd "M-a") 'backward-char)
(global-set-key (kbd "C-a") 'backward-char)

This uses emacs key notation. In short M-a represents Alt+a, C-a represents Ctl+a. For these two examples the key is bound to emacs function backward-char.

When you define a global key that conflicts with ergoemacs-mode keybindings (after loading ergoemacs-mode) the binding will no longer active in ergoemacs-mode. Therefore, the binding should be active in most places in emacs.

There is still a possibility that another major or minor mode will bind the key. If that occurs, you can locally override the bindings. Assuming this occurs in silly-mode, you can usually override the settings by setting the keys locally in the major-mode:

(add-hook 'silly-mode-hook
          (lambda()
            (local-set-key (kbd "C-a") 'backward-char)))

Also note that the order that you define the global-keys matter when using ergoemacs-mode. For example, if you decide to change the global binding before ergoemacs-mode loads, the key definition is typically ignored when ergoemacs-mode is enabled. For example:

(global-set-key (kbd "M-a") 'backward-char)
(require 'ergoemacs-mode)
(ergoemacs-mode 1)

The keyboard definition for backward-char is ignored when ergoemacs-mode is enabled. However, if you use:

(require 'ergoemacs-mode)
(global-set-key (kbd "M-a") 'backward-char)
(ergoemacs-mode 1)

then ergoemacs-mode will respect the Alt+a backward character assignment.

This behavior allows ergoemacs keybindings to override the keys in an emacs configuration like prelude, emacs-live, etc. If you do not like this behavior, you can turn it off by:

(global-set-key (kbd "M-a") 'backward-char)
(setq ergoemacs-ignore-prev-global nil) ; Will not ignore any globally
                                        ; defined keybinding
(require 'ergoemacs-mode)
(ergoemacs-mode 1)

In this example Alt+a will be bound to backward-char for ergoemacs-mode as well as globally.

If you are loading ergoemacs-mode before loading one of these emacs settings and you want to ignore the keybindings of the settings, you can also ignore them by using the following code

(global-set-key (kbd "M-a") 'backward-char)
(require 'ergoemacs-mode)
(ergoemacs-mode 1)

;; Load starter kit here
;; Ignore starter-kit keys in ergoemacs-mode
(ergoemacs-ignore-prev-global) ; Globally defined keys defined
                               ; before this point are ignored

One of the disadvantages of using globally defined keys it they will be bound globally even if ergoemacs-mode is not active. Additionally, they are not Layout independent. For example, defining Alt+j on QWERTY will not change to Alt+n for colemak.