Principles and Specification for Mnemonic Ethiopic Keyboards

1.1 Purpose of this document

This document defines the principles behind the Ethiopic input methods provided by The Ge'ez Frontier Foundation. These principles have been developed and refined over time to their present state of maturity. The principles are intended to be language and hardware device independent and sound enough that independent parties could implement them for a target device and arrive at approximately, if not identically, the same result.

The principles defined here are best practices for symbol mappings between Ethiopic script and some other target script for the purpose of text entry. The principles then are applicable to input devices where a character key is present in some form to map onto. The principles are not intended for devices that utilize other kinds of text entry, such as a handwriting recognition system (e.g. "Graffiti" for PDAs).

The principles have been developed with hardware keyboards as the primary devices for implementation. The principles remain valid as new constraints of key availability and geometry are imposed upon the traditional keyboard in modern devices. The QWERTY keyboard will be used in an example implementation.

1.2 Background on Ethiopic Keyboards

Over the last twenty years a few software vendors have introduced a physical Ethiopic keyboard which with all but one recent exception was modeled after the Ethiopic typewriter. While innovative these hardware devices also required proprietary software to operate, were prohibitively expense, and ultimately did not prevail in the market place. Ethiopic script today does not benefit from specialized keyboard hardware designed specifically for it. Ethiopic script then will be entered via mappings some keyboard device designed for the users of another script and language (e.g. an English, French, Arabic keyboard). This is achieved by mapping the Ethiopic characters to the symbols of the keyboard device. The mappings in turn are either positional based on the geometry of the Ethiopic typewriter, or phonetically based on the correspondence in the relationship of the letter sounds with functional mappings of punctuation. This specification focuses on the later approach.

At the present time no government institute, or private standards body, recognizes or endorses a specification for an Ethiopic input method. Attempts have been made in recent years but for various reasons no success has yet been met. This status may change in the near future. As the Ethiopic input methods found today typically vary by roughly 10-15% in their mappings, it can be expected that when a recognized standard arrives that it will not be significantly different from an existing input methods, nor identical. Thus any Ethiopic input method support now would be subject to later revision when a standard becomes available.

2.1 Script vs Language

Seemingly intuitive, the notion of an "Ethiopic keyboard" is a fallacy in practice. "Ethiopic" connotes a single script but when we consider its use by numerous languages the reason becomes clear. As with other scripts like Latin, Arabic, Cyrillic, etc, in use by multiple languages, the speakers of a given language will use some subset of the script and may have no exposure to the letters and symbols in use by other languages which use a different subset. Accordingly a single unifying input method (and keyboard hardware) is undesirable to the users of any specific language employing the script. Such an input method would lead to slower rates of entry (keying) and lower quality documents as unintended entries (typos) are made of out-of-language letter symbols.

While present, the adverse impact on languages using Ethiopic script under Unicode 3.0 has not been detrimental to writing. With the introduction of an additional 116 symbols under Unicode 4.1 the impact that a unified Ethiopic keyboard would have would be much more pronounced. It is a goal of this specification that the input methods defined will minimize the opportunity for spelling and symbol errors to occur. Accordingly, input methods defined herein are restricted in scope to only those symbols in the inventory of a given a given language community.

A language neutral input method is however specified as a convenience for those rare instances when out-of-language or archaic symbols are desired by a user. A unified Ethiopic keyboard for these special cases is desirable to users over either a character-picker utility or versus having to install numerous input methods that would cover all Ethiopic languages to then have access to all Ethiopic symbols.

2.2 General Principles

A few guiding general principles are applied to all input methods specified.

Principle of Standards Conformance: All character specified in a mapping must an encoded character under the Unicode standard. The non-letter symbols of QSAE ES 781:2002 must also available in an Ethiopic input method (excluding the Zaima (tonal) marks and archaic punctuation required only for Ge'ez).

Principle of Linguistic Scoping: Input methods are specified on a per-language basis where the character repertoire of the target language is first identified and will be in keeping with the repertoire applied in school systems and corpus.

Principle of Utility: All native punctuation of the underlying keyboard device must remain available without a return toggle to the native input method. This principle also helps support conformance to the ES 781:2002 standard for Ethiopic punctuation. Ethiopic script is much more frequently mixed with non-Ethiopic punctuation and numbers than with letters.

Principle of Ergonomics: While adhering to mnemonic principles keystrokes are kept to a minimum to the extent possible. Homophonic redundancy is common in Ethiopic orthographies and when such cases occur letter frequency will direct mappings whereby the most frequently occurring homophonic symbol will have the fewest keystrokes to render.

Principle of Productivity: The input method should minimize the mechanical and cognitive effort exerted in the keying of a document while also keeping symbol errors to a minimum. The Principles of Linguistic Scoping and Ergonomics directly support the Principle of Productivity.

2.3 Mnemonic Principles

Mnemonic principles are defined that lead to intuitive results requiring little or no education on the part of the user. It is assumed that the user is familiar with the script that the target device natively supports and that the Ethiopic character set is being mapped onto.

Principle of Character Class Continuity:

Letters are mapped to letters.
Numbers are mapped to numbers.
Punctuation is mapped to punctuation.

Principle of Phonological Continuity: Letters are mapped between scripts in accordance with transliteration and transcription norms whereby a phonemic correspondence is maintained (give reference). When the target keyboard devise is designed for a script where letter case is present, the vowel component of a syllograph (the "V" of a "CV" pattern) is mapped to the target script case-independently. That is, the vowel component is mapped to the both the uppercase and lowercase forms of the vowel in the target script.

Principle of Continuity of Quantity: Numbers are mapped between scripts with respect to their value.

Principle of Continuity of Function: Punctuation is mapped between scripts with respect to their functional role in a body of text.

Principle of Graphical Continuity: When a functional equivalent does not exist for punctuation on the target keyboard devise, the punctuation should be mapped on a graphical basis. Either by similarity in shape between the punctuation glyphs in whole or constituent parts. A strong preference exists that some Ethiopic punctuation be mapped graphically and not functionally.

Principle of Kinesthetic-Visual Feedback: For every keystrike some visual event will occur on screen related to the Ethiopic character composition at the cursor. This principle also means that the input method shall not employ dead keys.

3.1 Letters

3.2 Punctuation

Punctuation use in Ethiopic writing practice find a modern and classical use. Some Western punctuation have become common in modern writing practices as well. As per the Principle of Character Class Continuity keyboard punctuation is mapped to Ethiopic punctuation. These mappings will be glyph based orf functional based depending on which associations has been found to be stronger. Punctuation mappings apply to all Ethiopic language input methods unless otherwise specified.

Entry of Modern Punctuation: Input mappings are defined for all While Ethiopic Combining Gemination Mark is not a punctuation symbol, punctuation is specified for its entry (for lack of a character class analog in QWERTY keyboards to map to), thus its listing here.

Entry of Archaic Punctuation: Input mappings for punctuation no longer in modern use are defined for the Ge'ez and "Unified Ethiopic" input methods only. Continual strikes of the colon key will render additional multi-dot symbols. The mappings of ":+", ":#" and ":?" are applied for transliteration conventions.

Entry of Latin Punctuation Used in Ethiopic Writing: Input mappings are defined for Latin punctuation from ES 781 that are frequent in Ethiopic writing but not easily available on a regular QWERTY keyboard.

A Note on "Smart Quotes": The guillemets (left and right pointing single and double angle quotation marks) are the default style for Ethiopic quotation. The guillemets could be provided by mappings onto Latin apostrophe and quotation mark where "smart quoting" is applied. If this implementation approach is chosen, the apostrophe and quotation symbols should then be provided through a double-strike of their respective keys in keeping with the Principle of Utility and ES 781.

A Note on Punctuation Following Numbers: The Latin script comma is used an order delimiter in numeric sequences as is Latin colon in time representations. A common typographical error is to use Ethiopic comma in a numeric sequence and Ethiopic Wordspace in a time representation. An auto-correct feature may be applied here when these symbols are found bounded on both sides by numeric symbols.

3.3 Numerals

The Ethiopic numeral system introduces additional complexity to an input method as a consequence of its non-digital basis. The Ethiopic numeral system is in a family of letter based numeral systems along with the Coptic and Roman systems which it resembles. Three levels of support for the numeral system are specified here. An input method implementation may then provide the highest level that an underlying software framework is capable of supporting.

Under modern writing practices the westernized Arabic digits, 0-9, are the default numeral system used in math, commerce and in general. Accordingly, the western digits will be the default for an Ethiopic input method and the Ethiopic numerals will be entered by a context change marker followed by the appropriate value given in the native numeral system of the keyboard device. For a QWERTY keyboard the context change marker is apostrophe and is chosen for its easy to type position and rare use in Ethiopic practices.

The Ethiopic numeral system is the default numeral system for the Ge'ez and "Unified Ethiopic" input methods where the context marker then indicates a change to western numeral entry.

Minimal Support Level: At the minimal support level only direct mappings from western digits onto a single Ethiopic numeral character is required. The mapping from value 1,000 onto Ethiopic ፲፻ shown in the table below is optional at the minimal level because it is a multi character Ethiopic numeric sequence. It is recommended however to help provide continuity in the orders of ten up to the numeral system radix.

Intermediate Support Level: At the intermediate support level the full minimal level is supported and additional mapping are provided for orders of ten up to two cycles of the Ethiopic radix (፼፼) or 10⁸. Additional mappings at the intermediate level:

Maximal Support Level At the maximal support level mapped key entry would be replaced with algorithmic determination of the Ethiopic numeric sequence from the value of the western sequence that has been keyed (Ref: http://ethiopic.org/Numerals/). Here no upper bound is specified for the numeric value that must be supported. Individual implementers may make a decision based on the buffer sizes for holding an Ethiopic sequence or other practical criteria.

3.4 Tonal Marks

The Ethiopic Tonal Marks, as the symbols are identified in the Unicode standard, are understood better as non-neumic, ekphonetic annotation marks. No precedence exists for their mechanical input in publishing system -either hardware (e.g. typewriter) or software based. The method for keyed input specified here employs the underscore symbol "_" which is otherwise unused in Ethiopic writing practices, followed by a digit key corresponding to the sort order of the symbol (the mapping is not based on value but position of the digits in the standard layout starting with "1" and ending with "0"). For input method frameworks that support it, it is recommended that an over-the-spot menu be used to present the symbols to the typist for selection.

Mappings for the Ethiopic Tonal Marks are only applicable to the Ge'ez and "Unified Ethiopic" input methods.

No strong mnemonic correspondence has been found for the symbols and the keys available on computer keyboards. The abbreviation of the symbol names may provide a suitable mnemonic that would be preferable to the numeral based entry specified here. Such a system is being evaluated presently and is complicated by variation in the symbol names that has been found to occur. This specification will be updated later if a consensus mnemonic convention is reached.