APL is a symbolic rather than a lexical language. The primitive functions of most computer languages are represented by a few symbols, such as + and /, and many reserved words, such as for and time(). The primitive functions and operators of APL are represented almost entirely by single-character symbols.
Before the definition of Unicode, APL implementers used custom fonts, in which many standard ASCII glyphs were replaced by APL glyphs. Older articles in our archive used these character-mapped fonts to produce camera-ready copy for printing.
In principle, it is possible to display these articles accurately in a browser where the appropriate character-mapped fonts have been installed. Our policy is rather to convert the APL code in the articles in our archive to Unicode, which can be displayed correctly on most machines regardless of what fonts are installed.
Converting all the remaining character-mapped code to Unicode is likely to take some time. If you are interested in a particular article, please let us know, and we will give it priority.