APL characters have been divide into two groups, the Alphabetics and the Non-Alphabetics.
A to Z andThe reason for this had to do with the technology available. The computer terminals of the day were mechanical and used a physical type-ball and a ribbon to print on paper. The type-ball held only about a hundred symbols. This meant that there were not enough positions available for all the APL symbols. There was an "underbar" that was composed, for example, with the letter capital "A" by first printing one and then printing the other to produce "A".
A to Z.
When the glass front terminal (the video display terminal) became available, this particular limitation was removed. In more recent releases of APL designed to run on computers with video display units (monitors) the alphabetics have been
a to z and
A to Z.
This was not done in a uniform way by all implementers. Some implementers took different attitudes about whether the A to Z corresponds to "a to z" or to "A to Z". This dichotomy persists today.
Moreover, at least one implementer added to the confusion by including three copies of the alphabet,
a to z,
A to Z, and
A to Z.
The APL Working Group ( ISO-IEC / JTC1 / SC22 / WG3 ) has taken the position that ISO Standard APL uses only two copies of the alphabet, and they are usually rendered a to z and A to Z.
The APL Working group has identified 131 non-alphabetic characters that have appeared in various APL implementations, and these are the subject of our tables here.
There are three categories of tables.
CD1 If you are reading this page from a computer with a slow connection to the outside world, be aware that the four pages here might take some time. See the sizes in the file below.
The above four pages are the four Tables from Annex A of CD1, as submitted by the APL Working Group in the as "Character Repertoire for APL". Committee Draft 1
Those who follow standards activity may like to know that it has been assigned the document number
ISO-IEC / JCT1 / SC22 / N3067
and is available as the "official" distribution of SC22: http://anubis.dkuug.dk/jtc1/sc22/open/n3067.pdf,
These Transition Tables were constructed to assist in the transition from CD1 to WD2, but may be of interest for their own sake. They contain much the same information as was given for the 131 elements shown in the "Tables of CD 1", except for the following changes:
The APL Working Group requested and was granted a change from U+25AF to U+2395.
There is some redundancy here, since the numbers N, P, and R satisfy the following identity:
N = (R-1) + 33 * (P-1)
The Tables for Working Draft 2 were developed using the tables for CD1 and the Transition Tables above.
Last Updated on 2000/02/10
By Lee Dickey