Talk:Digital encoding of APL symbols

Underscored alphabetics:

When APL was first made available on IBM printing terminals in the 1960s, the typing element did not enough room for lower case a-z. Thus underscored alphabetics were an available way to get another "case". Possibly the Unicode designers thought that underscoring was a text attribute, not unlike the underscore, bold, italic, etc. as one would find in MS Word. This is not true with APL - underscored characters were distinct from non-underscored characters and allowed a kind of upper / lower case. Only A-Z and the "delta" symbol could be underscored. With the IBM 3279 display terminals, one could now have three alphabet cases in programs - upper and lower case, plus underscored characters.

Usage of underscored alphabetic characters are considered by many APL programmers to be obsolete, not modern, and in bad style. APL+Win has eliminated them from their version of the language. Other implementations still support them, but consider them deprecated.

188.60.207.142 (talk) 17:21, 28 May 2011 (UTC)[reply]

I've used APL on mainframe since the 70ies and still use it on my OS/2 PC today (for math). PC-APL started with lower-case instead of underline via the ALT-key. On mainframe programs (OS/360,OS/370, VM, ...) it was some kind of programmers agreement to use underlines for global variables between functions (same workspace), except for text-headlines, as a better way of readability. APL-workspaces have also been portable from mainframe to PC and i still use most if my statistical work downloaded up to now. Actual use some stochastic work on demographics. Beside FORTRAN-programs APL is my main "calculation suite" if Lotus123(OS/2) or Excel(Win) does not fit. regards from a retired IBM-Dinosaur.......