Background

The proposal for encoding of Emoji symbols as Unicode characters covers the Emoji symbols that are in widespread use by DoCoMo, KDDI and Softbank for their mobile phone networks. These symbols are encoded in carrier-specific versions of Shift-JIS (as User-Defined Characters), and, in the case of KDDI, in a carrier-specific version of ISO-2022-JP. There are mapping tables in use in the industry between these character sets, with both roundtrip and fallback mappings. These symbols are also supported in web mail services by Yahoo! Mail and Google Mail. (Yahoo! Mail currently supports a subset.) (The original proposal also included nine symbols defined by Google, but they were withdrawn from later versions.)

We are taking into consideration the following factors in developing the proposal:

1. Source separation rule: If a single carrier separates two characters (anywhere in the character set, so including standard JIS codes), then we mapped them to two separate Unicode characters. (This is a hard and fast rule.)
   
2. Reuse: We mapped to existing Unicode symbols where appropriate.
3. Separating generic symbols: If Unicode had a set of related symbols, but no one character in the set was as generic as in the Emoji symbol sets, then we encoded a new character. For example, the Emoji sets do not distinguish between waxing and waning crescent moons.
   
4. Colors and Animation: We encoded symbols as characters, abstracting away from colors and animation. We only distinguished by nominal color or animation for the source separation rule. (See Character Names below.)
5. Existing cross-mapping tables: We followed the tables mentioned above as much as possible, but we tentatively disunified in some cases where the visual images were very different and not semantically associated. For example:
1. We disunified the 'M' symbol for Metro from the Metro train image. The 'M' symbol would have translation problems. (This is similar to the problems with the international currency symbol and the proposal for a "generic decimal separator".)
   
2. On the other hand, we unified the sets of Zodiac symbols, even though the images shown by carriers vary widely. This is because they clearly belong to a cohesive set which corresponds across carriers.
   
6. Least-marked common symbol: For a set of symbols which each could map to an existing Unicode code point, we chose the symbol that was shared among the most carriers (according to the cross-mapping tables) and had the least-marked form.

Note: We tried to avoid disunification in Unicode where there are round-trip mappings between carriers. However, where necessary, the disunification can be done. As the following diagram illustrates, roundtrip mappings between carrier Shift-JIS character sets can be maintained, by having the mapping tables between Unicode and each carrier's Shift-JIS version use appropriate fallback mappings.

Character Names

Proposed character names are typically based on the glosses of the carrier symbols or the visual appearance. Based on the consensus from discussions in the UTC, we used the following guidelines:

Documents

See the latest charts:

• Chart of symbols that are unified or proposed for new encoding
• Chart with all symbols and all data
• Chart legend
  

L2 document links require access privileges granted to Unicode Consortium members.

2009-04-27: L2/09-153 Emoji Ad-Hoc Meeting Report (=N3636)