This discussion has sparked a few lively contributions and brought up some important points, so even though it may have been beaten to death and Robert has announced his intent to move it to another forum, I still have some comments that may be pertinent in the AMS discussion.
I was a little disappointed that others were drawn into the debate over the relative merits of the constants 3.14 versus 6.28, since this issue is completely irrelevant to the question of encoding a new "2 pi" symbol in Unicode. For most of us, at least, the objection to encoding this symbol in Unicode has nothing at all to do with its theoretical usefulness, but its lack of currency at the present time. Whether the symbol would be useful or represents an important mathematical constant is not the point. It must be commonly used, or at least recognized, within the field. It is not a question of whether typographers would personally see the benefit of such a symbol (BTW, not all of us are typographers; this list also includes software developers, linguists, and standardization types). The symbol must already be in use, as determined by a sufficient body of work. Mathematicians are researchers; they know it is not sufficient to cite a single article, especially one written by oneself or one's associates, as a "body of work" to demonstrate the use or non-use of something. The 2 pi symbol is an experiment, and it is important to remember that not all experiments are successful! Some proposed characters, words, ideas, TV shows, etc. do not achieve a sufficient level of popularity and are discarded. As Rick McGowan indicated, it is not a goal of Unicode to encode characters that someone, even a lot of people, believe *might* (or should) achieve widespread use; they must already be in use (with one notable exception; see below). Think of a dictionary. New words are invented all the time, sometimes intentionally by companies or advertisers, yet nobody would think of going to Merriam-Webster and asking them to include their newly invented word in the next edition of the dictionary so that it will be recognized and will gain greater use. Rather, the word has to gain a certain degree of acceptance *before* it is enshrined in the dictionary. The same is true for encoding characters in Unicode. If Dr. Beebe suggested trying to get the 2 pi character into Unicode to stimulate its adoption, then he does not understand the principles and policies of Unicode. I wonder if there is a perception, because of the extensive work done by the Unicode Consortium and ISO/IEC JTC1/SC2/WG2 in encoding over 95,000 characters, that any newly invented character or symbol can be encoded just for the asking. The fact is that there are over 95,000 characters in Unicode, not because the relevant committees are fast and loose in encoding newly invented characters, but because there really are that many well-attested characters in the world. (Well, OK, minus some of the compatibility characters.) David Starner mentioned the proposed "copyleft" sign. This was a reversed copyright sign (roughly representable by U+0254 plus U+20DD) which enjoys some use by the Free Software Foundation and the GNU project to signify a legal agreement that is similar to, but different from, a traditional copyright. The symbol is apparently recognized by many adherents to the "free software" movement, probably more people than would recognize the 2 pi symbol. But it turned out to be used primarily as a logo to promote the movement, rather than as a plain-text character to indicate the legal status of a work, as U+00A9 COPYRIGHT SIGN would be. In fact, it would almost certainly not be recognized at all by non-FSF, non-GNU people except as a whimsical play on the copyright sign (the suggested name demonstrated the "anti-copyright" religion of the proponents). The classic exception to the principle that a symbol must be in current use before it can be encoded is U+20AC EURO SIGN. This character was encoded in Unicode 2.1 in 1998, long before most people -- including those who are now converting their money to euros -- had ever seen it. But there was a difference: the Euro sign was invented by, and had the full support of, the European Monetary Union, and was *guaranteed* to become a commonly used symbol, something that cannot normally be said of most newly invented symbols. Even though the symbol had never been used before, there was no question that it would "catch on." A good measure of whether the 2 pi symbol has become sufficiently well recognized to be added to Unicode is whether it can be used in works like the JOMA article without having to explain or justify its usage beyond that which would be needed for any other symbol. I hope that this discussion has shed some light on an important principle of Unicode for Robert (and perhaps for others), so that the AMS discussion can proceed in a productive manner. The bottom line, however, will certainly be that Robert's 2 pi symbol is no Euro sign, with a guarantee of future utility; it will have to demonstrate that utility before being encoded. -Doug Ewell Fullerton, California
