Editing Ergonomic keyboard layouts (section)

===Ergolinear Split-case designs===

Following the development of the Ergolinear form factor, the developers Ian Douglas and Xay Voong continued with their attempts to reach layout nirvana.

As is common in this field, inventors work with frequency charts of letters, bigrams, trigrams, etc. in an attempt to find a better layout.

The typical letter frequency order for English is usually a variation of this order, from Michael Dickens:

SPC etaoinsrhldcumfgpyw ENT b,.vk-"_'x)(;0j1q=2:z/*!?$35>{}49[]867\+|&<%@#^`~

But this is not the whole story. One day, Ian stumbled across a frequency chart taken from a large American corpus, which looked like this:

etaoinsrhldcumpfg.ywb-,v0k1TAIS2C'"/3ED9:MN=RP;4OB5)L(HFx8W67G_UjqzJ<?Y@*VK!|$~[]%X&+#QZ}{>`\^

Apart from some order difference, the biggest difference was the separation of uppercase and lowercase letters. It suddenly dawned on him that we type mostly lower case letters, and so we should optimise for that.
This insight, together with the use of Arensito-style AltGr, led to the birth of the split-case design, where the upper case for a letter is on a different key to its lower case version.

Ideally, the optimising should work strictly according to frequency, but as a help, Ian decided to be a little less optimal, and split the keyboard into three main rows:

* Capital letters
* Lower case letters
* Punctuation and digits.

This led to the acronym C - L - P which was turned into the word Seelpy, as a name for this type of layout.

The initial version (Seelpy 1) looks like this:

[[File:Seelpy-1-ergolinear-kla.jpg|frameless|Seelpy 1 Ergolinear]]

Ian further refined this layout until it became unbeatable on Den1 scoring on KLA.

However Xay decided to pursue full optimisation, which entails mixing uppercase, lowercase, punctuation and digits, to achieve the best score.

This version of the Split Case came to be called Essie, from the acronym S - C. Alternative names use CLP even though this no longer implies strict separation by row.

A version of such a layout looks like this:

[[File:Essie-3-wip.ergolinear.png|frameless|Essie 3 work in progress]]

A comparison of scores, using Alice Chapter One on KLA: (higher is better)

[[File:Seelpy-patrick.png|frameless|Seelpy and Essie scores on KLA]]

A comparison of scores, using Alice Chapter One on Den1 scoring of KLA: (lower is better)

[[File:Seelpy-den1.png|frameless|Seelpy and Essie scores on Den1 scoring on KLA]]

These layouts may be too difficult to use in practice.