Digital encoding of APL symbols

Prior to the wide adoption of Unicode, a number of special-purpose EBCDIC and non-EBCDIC code pages were used to represent the symbols required for writing APL.

Due to its origins on IBM Selectric-based teleprinters, APL symbols have traditionally been represented on the wire using a unique, non-standard character set.

Over time, with the universal use of high-quality graphic display, printing devices and Unicode support, the APL character font problem has largely been eliminated.

As of 2010, Unicode allows APL to be stored in text files, published in print and on the web, and shared through email and instant messaging.

Unicode's Latin Extended Additional block includes the following capital "Line Below" characters with the macron below diacritic, for Semitic transcription (it includes a pre-composed ẖ only in lowercase): However, this does not cover the entire ISO basic Latin alphabet, and IBM's reference glyphs for the APL characters show them both underlined and oblique,[2] and tables simulating them with markup may follow suit.

This makes it easier for an English-language speaker to type APL on a non-APL keyboard, providing one has visual feedback on one's screen.

This extended the graphic abilities of the earlier teleprinters, but made it more complex to correct errors and edit program lines.

Finally, the symbols were ratified in Unicode and given specific code points, with unambiguous interpretations, independently of the graphic font.