There seems to be a rule that whenever a computer keyboard gets too close to the microscope a new program for counting pollen arises. However, many programs "emulate" mechanical counters only, whereas even the oldest XT can do much more (Davis, 1993). In my POLPAL (Walanus, 1991) a kind of optimization of the taxa codes is applied. In the process of counting, two things should be minimized: the number of keystrokes and the amount of human memory occupied by the codes. That is possible under the obvious assumption that some taxa are frequent, some are rare and the rest are very rare.
Up to the ten most frequent taxa are coded by the function keys <F1>..<F10>. The next group (in principle up to 26 x 26 = 676 taxa) is coded by the sequence of two letter keys. The remaining "very rare" taxa are coded by the three-letter codes, which are four keystrokes in fact, because the space bar must be pressed before the letters.
How many taxa should be coded with one-, two- or three-keys codes is a matter of which kind of effort is preferred: to search for the key on the keyboard or to remember codes. It must be mentioned that a codes dictionary is available in POLPAL any time by pressing <Enter> and the first letter of the taxon's name. However, searching for the code on the screen is the most time-consuming task during counting. It is really a personal decision whether it is worth to remember: <F5> = Alnus, and use one keystroke per Alnus grain, or to use: <a><l> = Alnus, easy to remember but with the 100% additional wear to the finger. Only the most frequent taxa should be coded by <Fn> keys. The less frequent taxa are coded by the two-letter codes. However, like the <Fn>'s, not all possible pairs of letters must be used. There is no reason to code Corylus avellana by, say, <i><y> because <c><o>, <c><a> and comparable options are already occupied. Certainly, the three-letter <c><o><r> is a pretty combination for remembrance.
The rareness of a taxon can be estimated automatically. Having to use the dictionary frequently to look up a taxon's code will soon fix the combination in your long-term memory!
Reference.
Davis, O.K. 1993. Program sources. INQUA - Commission for the Study of the Holocene, Working Group on Data-Handling Methods Newsletter 10:30-33.
Ralska-Jasiewiczowa, M. and Walanus, A. 1991. Polish palynolgical database (POLPAL) in course of building. INQUA - Commission for the Study of the Holocene, Working Group on Data-Handling Methods Newsletter 5:1-2.