Digital encoding of APL symbols
The programming language APL uses a number of symbols, rather than words from natural language, to identify operations, similarly to mathematical 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.
Character sets
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. In the 1960s and 1970s, few terminal devices existed which could reproduce them, the most popular ones being the IBM 2741 and IBM 1050 fitted with a specific APL print head. 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.
Character repertoire
IBM assigns the following character IDs (GCGIDs) to APL syntax, which are used in the definitions of its code pages.[1][2]
| GCGID[2] | IBM name[1] | Unicode | Notes and other mappings |
|---|---|---|---|
| SL010000 | Up Stile (APL) | U+2308 ⌈ LEFT CEILING | |
| SL020000 | Down Stile (APL) | U+230A ⌊ LEFT FLOOR | |
| SL030000 | Del (APL) | U+2207 ∇ NABLA | |
| SL040000 | Del Tilde (APL) | U+236B ⍫ APL FUNCTIONAL SYMBOL DEL TILDE | |
| SL050000 | Del Stile (APL) | U+2352 ⍒ APL FUNCTIONAL SYMBOL DEL STILE | |
| SL060000 | Delta (APL) | U+2206 ∆ INCREMENT | |
| SL070000 | Delta Stile (APL) | U+234B ⍋ APL FUNCTIONAL SYMBOL DELTA STILE | |
| SL080000 | Circle (APL) | U+25CB ○ WHITE CIRCLE[3][4][5] | This is SM750000 in a non-APL context, for example, in the C0 replacement graphics from code page 437,[6] which code pages 907, 909 and 910 inherit some or all of, retaining SM750000 in the C0 area and also including SL080000 outside of it.[7][8][9] Both map to U+25CB. Compare SL590000 through SL620000 below. |
| SL090000 | Circle Stile (APL) | U+233D ⌽ APL FUNCTIONAL SYMBOL CIRCLE STILE | |
| SL100000 | Circle Slope (APL) | U+2349 ⍉ APL FUNCTIONAL SYMBOL CIRCLE BACKSLASH | |
| SL110000 | Circle Star (APL) | U+235F ⍟ APL FUNCTIONAL SYMBOL CIRCLE STAR | |
| SL120000 | Circle Bar | U+2296 ⊖ CIRCLED MINUS | |
| SL130000 | Quad Quote (APL) | U+235E ⍞ APL FUNCTIONAL SYMBOL QUOTE QUAD | |
| SL140000 | Quad Divide (APL) | U+2339 ⌹ APL FUNCTIONAL SYMBOL QUAD DIVIDE | |
| SL150000 | Slash Bar (APL) | U+233F ⌿ APL FUNCTIONAL SYMBOL SLASH BAR | |
| SL160000 | Slope Bar (APL) | U+2340 ⍀ APL FUNCTIONAL SYMBOL BACKSLASH BAR | |
| SL170000 | Up Caret Tilde (APL) | U+2372 ⍲ APL FUNCTIONAL SYMBOL UP CARET TILDE | |
| SL180000 | Down Caret Tilde (APL) | U+2371 ⍱ APL FUNCTIONAL SYMBOL DOWN CARET TILDE | |
| SL190000 | Down Tack Jot (APL) | U+234E ⍎ APL FUNCTIONAL SYMBOL DOWN TACK JOT | |
| SL200000 | Up Tack Jot (APL) | U+2355 ⍕ APL FUNCTIONAL SYMBOL UP TACK JOT | |
| SL210000 | Up Shoe Null (APL) | U+235D ⍝ APL FUNCTIONAL SYMBOL UP SHOE JOT | |
| SL220000 | Up Tack (APL) | U+22A4 ⊤ DOWN TACK[a] | |
| SL230000 | Down Tack (APL) | U+22A5 ⊥ UP TACK[a] | |
| SL240000 | Down Tack Up Tack (APL) | U+2336 ⌶ APL FUNCTIONAL SYMBOL I-BEAM | |
| SL250000 | Jot (APL) | U+2218 ∘ RING OPERATOR | |
| SL260000 | Left Bracket Right Bracket (APL) | U+2337 ⌷ APL FUNCTIONAL SYMBOL SQUISH QUAD | |
| SL270000 | Quad Jot (APL) | U+233B ⌻ APL FUNCTIONAL SYMBOL QUAD JOT | |
| SL280000 | Quad Slope (APL) | U+2342 ⍂ APL FUNCTIONAL SYMBOL QUAD BACKSLASH | |
| SL300000 | Equal Underbar (APL) | U+2261 ≡ IDENTICAL TO | |
| SL320000 | Diaeresis Dot (APL) | U+2235 ∵ BECAUSE | |
| SL330000 | Delta Underbar (APL) | U+2359 ⍙ APL FUNCTIONAL SYMBOL DELTA UNDERBAR | |
| SL340000 | Left Tack (APL) | U+22A2 ⊢ RIGHT TACK[a] | |
| SL350000 | Right Tack (APL) | U+22A3 ⊣ LEFT TACK[a] | |
| SL360000 | Quad (APL) | U+2395 ⎕ APL FUNCTIONAL SYMBOL QUAD | |
| SL370000 | Less Greater (APL) | U+22C4 ⋄ DIAMOND OPERATOR[3][4] | U+25CA ◊ LOZENGE, U+25C6 ◆ BLACK DIAMOND[5][10] |
| SL380000 | Stile (APL) | U+2223 ∣ DIVIDES[3][4] | U+2502 │ BOX DRAWINGS LIGHT VERTICAL[5][10] |
| SL400000 | Up Shoe (APL) | U+2229 ∩ INTERSECTION[3][4] | U+22C2 ⋂ N-ARY INTERSECTION[10][5] |
| SL410000 | Down Shoe (APL) | U+222A ∪ UNION[3][4] | U+22C3 ⋃ N-ARY UNION[10][5] |
| SL420000 | Left Shoe (APL) | U+2282 ⊂ SUBSET OF | |
| SL430000 | Right Shoe (APL) | U+2283 ⊃ SUPERSET OF | |
| SL440000 | Underbar (APL) | U+005F _ LOW LINE | |
| SL450000 | Diaeresis (APL) | U+00A8 ¨ DIAERESIS | |
| SL460000 | Tilde (APL) | U+223C ∼ TILDE OPERATOR[3][4] | Also mapped to U+007E ~ TILDE,[10][5] although SD190000 (U+007E in a non-APL context) co-occurs at 0xA1 (while SL460000 is at 0x80) in code page 213.[11] |
| SL500000 | Down Caret (APL) | U+2228 ∨ LOGICAL OR[10][5][3][4] | |
| SL510000 | Up Caret (APL) | U+2227 ∧ LOGICAL AND[3][4] | U+22C0 ⋀ N-ARY LOGICAL AND[10][5] |
| SL520000 | Less (APL) | U+003C < LESS-THAN SIGN | |
| SL530000 | Greater (APL) | U+003E > GREATER-THAN SIGN | |
| SL540000 | Divide (APL) | U+00F7 ÷ DIVISION SIGN | |
| SL550000 | Times (APL) | U+00D7 × MULTIPLICATION SIGN | |
| SL560000 | Not Greater (APL) | U+2264 ≤ LESS-THAN OR EQUAL TO | |
| SL570000 | Not Less (APL) | U+2265 ≥ GREATER-THAN OR EQUAL TO | |
| SL580000 | Quote Dot (APL) | U+0021 ! EXCLAMATION MARK[10][5][4] | SP020000 (U+0021 ! EXCLAMATION MARK in a non-APL context) co-occurs at 0x5A in code page 293 (SL580000 is at 0xDB in code pages 293 and 310).[11] Tachyonsoft lists U+01C3 ǃ LATIN LETTER RETROFLEX CLICK for SL580000.[3] |
| SL590000 | Left Arrow (APL) | U+2190 ← LEFTWARDS ARROW[3][4][5] | These arrows are SM300000, SM310000, SM320000 and SM330000 respectively in a non-APL context, for example, in the C0 replacement graphics from code page 437,[6] which code pages 907, 909 and 910 inherit some or all of.
Code pages 907 and 910 keep the non-APL GCGIDs for the C0 replacements but use the APL GCGIDs where the arrows appear outside of the C0 area, while code page 909 uses the APL GCGIDs multiple times, both for the C0 replacements and for between one and two occurrences of each of these arrows outside of the C0 area.[7][8][9] Compare SL080000 above. Duplicating C0 replacement graphics outside of the C0 area is not an uncommon practice in DOS code pages: compare, for example, the pilcrow and section sign in code page 850. |
| SL600000 | Right Arrow (APL) | U+2192 → RIGHTWARDS ARROW[3][4][5] | |
| SL610000 | Up Arrow (APL) | U+2191 ↑ UPWARDS ARROW[3][4][5] | |
| SL620000 | Down Arrow (APL) | U+2193 ↓ DOWNWARDS ARROW[3][4][5] | |
| SL630000 | Overbar (APL) | U+203E ‾ OVERLINE | |
| SL640000 | Slope (APL) | U+005C \ REVERSE SOLIDUS[10][5][4] | Also mapped to U+2216 ∖ SET MINUS.[3] SM070000 (U+005C \ REVERSE SOLIDUS in a non-APL context) co-occurs at 0x5A (while SL640000 is at 0xB7) in code page 293.[11] |
| SL650000 | Star (APL) | U+22C6 ⋆ STAR OPERATOR[4] | U+002A * ASTERISK[12] |
| SL660000 | Quote (APL) | U+0027 ' APOSTROPHE | |
| SL670000 | Left Parenthesis (APL) | U+0028 ( LEFT PARENTHESIS | |
| SL680000 | Right Parenthesis (APL) | U+0029 ) RIGHT PARENTHESIS | |
| SL690000 | Bar (APL) | U+002D - HYPHEN-MINUS[12][4][5] | U+2212 − MINUS SIGN |
| SL700000 | Query (APL) | U+003F ? QUESTION MARK | |
| SL710000 | Alpha (APL) | U+237A ⍺ APL FUNCTIONAL SYMBOL ALPHA[3][4] | U+03B1 α GREEK SMALL LETTER ALPHA[10][5] |
| SL720000 | Epsilon (APL) | U+220A ∊ SMALL ELEMENT OF[4] | U+03B5 ε GREEK SMALL LETTER EPSILON,[10][5] U+2208 ∈ ELEMENT OF[3] |
| SL730000 | Iota (APL) | U+2373 ⍳ APL FUNCTIONAL SYMBOL IOTA[3][4] | U+03B9 ι GREEK SMALL LETTER IOTA[10][5] |
| SL740000 | Rho (APL) | U+2374 ⍴ APL FUNCTIONAL SYMBOL RHO[3][4] | U+03C1 ρ GREEK SMALL LETTER RHO[10][5] |
| SL750000 | Omega (APL) | U+2375 ⍵ APL FUNCTIONAL SYMBOL OMEGA[3][4] | U+03C9 ω GREEK SMALL LETTER OMEGA[10][5] |
| SL760000 | Slash (APL) | U+002F / SOLIDUS | |
| SL770000 | Left Bracket (APL) | U+005B [ LEFT SQUARE BRACKET | |
| SL780000 | Right Bracket (APL) | U+005D ] RIGHT SQUARE BRACKET | |
| SL790000 | Plus (APL) | U+002B + PLUS SIGN | |
| SL800000 | Semicolon (APL) | U+003B ; SEMICOLON | |
| SL810000 | Equal (APL) | U+003D = EQUALS SIGN | |
| SL820000 | Not Equal (APL) | U+2260 ≠ NOT EQUAL TO | |
| SL830000 | Colon (APL) | U+003A : COLON[5][4] | Form with fullwidth attribute set (SL830080) is used for 0xA1C3 (i.e. U+2236 ∶ RATIO) in EUC-CN.[13] |
| SL840000 | Dot (APL) | U+002E . FULL STOP | |
| SL850000 | Comma (APL) | U+002C , COMMA | |
| SL860000 | Iota Underbar (APL) | U+2378 ⍸ APL FUNCTIONAL SYMBOL IOTA UNDERBAR | |
| SL870000 | Epsilon Underbar (APL) | U+2377 ⍷ APL FUNCTIONAL SYMBOL EPSILON UNDERBAR |
EBCDIC code pages
Code page 293
Code page 293 (CCSID 293),[14] called "APL (USA)", is an EBCDIC code page which includes APL symbols, in addition to preserving the basic Latin letters and Western Arabic numerals at their usual EBCDIC locations.[11][12]
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
| 0x | NUL | SOH | STX | ETX | SEL | HT | RNL | DEL | GE | SPS | RPT | VT | FF | CR | SO | SI |
| 1x | DLE | DC1 | DC2 | DC3 | RES/ ENP |
NL | BS | POC | CAN | EM | UBS | CU1 | IFS | IGS | IRS | IUS/ ITB |
| 2x | DS | SOS | FS | WUS | BYP/ INP |
LF | ETB | ESC | SA | SFE | SM/ SW |
CSP | MFA | ENQ | ACK | BEL |
| 3x | SYN | IR | PP | TRN | NBS | EOT | SBS | IT | RFF | CU3 | DC4 | NAK | SUB | |||
| 4x | SP | 𝐴̲ | 𝐵̲ | 𝐶̲ | 𝐷̲ | 𝐸̲ | 𝐹̲ | 𝐺̲ | 𝐻̲ | 𝐼̲ | ¢ | . | < | ( | + | | |
| 5x | & | 𝐽̲ | 𝐾̲ | 𝐿̲ | 𝑀̲ | 𝑁̲ | 𝑂̲ | 𝑃̲ | 𝑄̲ | 𝑅̲ | ! | $ | ⋆/* | ) | ; | ¬ |
| 6x | -/− | / | 𝑆̲ | 𝑇̲ | 𝑈̲ | 𝑉̲ | 𝑊̲ | 𝑋̲ | 𝑌̲ | 𝑍̲ | ¦ | , | % | _ | > | ? |
| 7x | ⋄/◊/◆ | ∧/⋀ | ¨ | ⌻ | ⍸ | ⍷ | ⊢ | ⊣ | ∨ | ` | :/∶ | # | @ | ' | = | " |
| 8x | ∼/~ | a | b | c | d | e | f | g | h | i | ↑ | ↓ | ≤ | ⌈ | ⌊ | → |
| 9x | ⎕ | j | k | l | m | n | o | p | q | r | ⊃ | ⊂ | ○ | ← | ||
| Ax | ‾ | ~ | s | t | u | v | w | x | y | z | ∩/⋂ | ∪/⋃ | ⊥ | [ | ≥ | ∘ |
| Bx | ⍺/α | ∊/ε/∈ | ⍳/ι | ⍴/ρ | ⍵/ω | × | \/∖ | ÷ | ∇ | ∆ | ⊤ | ] | ≠ | ∣/│ | ||
| Cx | { | A | B | C | D | E | F | G | H | I | ⍲ | ⍱ | ⌷ | ⌽ | ⍂ | ⍉ |
| Dx | } | J | K | L | M | N | O | P | Q | R | ⌶ | !/ǃ | ⍒ | ⍋ | ⍞ | ⍝ |
| Ex | \ | ≡ | S | T | U | V | W | X | Y | Z | ⌿ | ⍀ | ∵ | ⊖ | ⌹ | ⍕ |
| Fx | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | ⍫ | ⍙ | ⍟ | ⍎ | EO |
Code page 310
Code page 310 ("Graphic Escape APL/TN") includes a larger gamut of symbols, but does not itself include the basic Latin letters or the basic digits.[16][3] It is used alongside Code page 37-2,[17] with the Code page 310 codes being prefixed by the Graphic Escape (EBCDIC 0x08)[18] control character.[5]
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
| 0x | ||||||||||||||||
| 1x | ||||||||||||||||
| 2x | ||||||||||||||||
| 3x | ||||||||||||||||
| 4x | SP | 𝐴̲ | 𝐵̲ | 𝐶̲ | 𝐷̲ | 𝐸̲ | 𝐹̲ | 𝐺̲ | 𝐻̲ | 𝐼̲ | ||||||
| 5x | 𝐽̲ | 𝐾̲ | 𝐿̲ | 𝑀̲ | 𝑁̲ | 𝑂̲ | 𝑃̲ | 𝑄̲ | 𝑅̲ | |||||||
| 6x | 𝑆̲ | 𝑇̲ | 𝑈̲ | 𝑉̲ | 𝑊̲ | 𝑋̲ | 𝑌̲ | 𝑍̲ | ||||||||
| 7x | ◊/⋄/◆[b] | ∧/⋀[b] | ¨ | ⌻ | ⍸ | ⍷ | ⊢ | ⊣ | ∨ | |||||||
| 8x | ∼/~[b] | ║ | ═ | ⎸ | ⎹ | │/⎥[b] | ↑ | ↓ | ≤ | ⌈ | ⌊ | → | ||||
| 9x | ⎕ | ▌ | ▐ | ▀ | ▄ | █/■[b] | ⊃ | ⊂ | ⌑/¤[b] | ○ | ± | ← | ||||
| Ax | ¯/‾[b] | ° | ─ | ∙/•[b] | ₙ | ∩/⋂[b] | ∪/⋃[b] | ⊥ | [ | ≥ | ∘ | |||||
| Bx | ⍺/α[b] | ∊/∈/ε[b] | ⍳/ι[b] | ⍴/ρ[b] | ⍵/ω[b] | × | ∖/\[b] | ÷ | ∇ | ∆ | ⊤ | ] | ≠ | ∣/│[b] | ||
| Cx | { | ⁽ | ⁺/+[b] | ■/∎[b] | └ | ┌ | ├ | ┴ | § | ⍲ | ⍱ | ⌷ | ⌽ | ⍂ | ⍉ | |
| Dx | } | ⁾ | ⁻/-[b] | ┼ | ┘ | ┐ | ┤ | ┬ | ¶ | ⌶ | ǃ/![b] | ⍒ | ⍋ | ⍞ | ⍝ | |
| Ex | ≡ | ₁ | ₂ | ₃ | ⍤[c] | ⍥[c] | ⍪[c] | €[c] | ⌿ | ⍀ | ∵ | ⊖ | ⌹ | ⍕ | ||
| Fx | ⁰ | ¹ | ² | ³ | ⁴ | ⁵ | ⁶ | ⁷ | ⁸ | ⁹ | ⍫ | ⍙ | ⍟ | ⍎ |
Code page 351
Code page 351 ("GDDM Default (USA)")[20] contains most of the characters of Code page 293 and Code page 310 (except ⍷, epsilon with underline) in addition to the letters and digits, by replacing several control characters with symbols.
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
| 0x | NUL | { | HT | ▀ | ⎹ | FF | CR | |||||||||
| 1x | NL | BS | ▌ | █ | ▐ | │ | ┐ | ┌ | └ | ┘ | ||||||
| 2x | ⁽ | ⁾ | ⁺ | ⁻ | } | LF | ⍸ | ║ | ▄ | ═ | ⎸ | § | ┼ | ─ | ⊢ | ⊣ |
| 3x | ⁰ | ¹ | ² | ³ | ⁴ | ⁵ | ⁶ | ⁷ | ⁸ | ⁹ | ¶ | ┬ | ├ | ┴ | ┤ | |
| 4x | SP | 𝐴̲ | 𝐵̲ | 𝐶̲ | 𝐷̲ | 𝐸̲ | 𝐹̲ | 𝐺̲ | 𝐻̲ | 𝐼̲ | ¢ | . | < | ( | + | | |
| 5x | & | 𝐽̲ | 𝐾̲ | 𝐿̲ | 𝑀̲ | 𝑁̲ | 𝑂̲ | 𝑃̲ | 𝑄̲ | 𝑅̲ | ! | $ | * | ) | ; | ¬ |
| 6x | - | / | 𝑆̲ | 𝑇̲ | 𝑈̲ | 𝑉̲ | 𝑊̲ | 𝑋̲ | 𝑌̲ | 𝑍̲ | ¦ | , | % | _ | > | ? |
| 7x | ⋄ | ∧ | ¨ | ₁ | ₂ | ₃ | ₙ | ° | ∨ | ` | : | # | @ | ' | = | " |
| 8x | ∼ | a | b | c | d | e | f | g | h | i | ↑ | ↓ | ≤ | ⌈ | ⌊ | → |
| 9x | ⎕ | j | k | l | m | n | o | p | q | r | ⊃ | ⊂ | ⌑ | ○ | ± | ← |
| Ax | ¯ | ~ | s | t | u | v | w | x | y | z | ∩ | ∪ | ⊥ | [ | ≥ | ∘ |
| Bx | ⍺ | ∈/∊ | ⍳ | ⍴ | ⍵ | ■ | × | ∖ / \ | ÷ | ∙ | ∇ | ∆ | ⊤ | ] | ≠ | ∣ |
| Cx | { | A | B | C | D | E | F | G | H | I | ⍲ | ⍱ | ⌷ | ⌽ | ⍂ | ⍉ |
| Dx | } | J | K | L | M | N | O | P | Q | R | ⌶ | ǃ/! | ⍒ | ⍋ | ⍞ | ⍝ |
| Ex | \ | ≡ | S | T | U | V | W | X | Y | Z | ⌿ | ⍀ | ∵ | ⊖ | ⌹ | ⍕ |
| Fx | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | ⌻ | ⍫ | ⍙ | ⍟ | ⍎ |
7-bit modified ASCII
Code page 371 (IR-68)
Code page 371,[21] registered for use with ISO/IEC 2022 as ISO-IR-68,[22][4] is a 7-bit heavily modified ASCII, designed by the APL Working Group of the Canadian Standards Association, intended for use with APL in an environment allowing overstriking of characters using the BS (backspace, 0x08) control code.[22][4]
8-bit modified and/or extended ASCII
Code page 907
Code page 907 is used by the IBM 3812, like code page 906. Differences from code page 437 are shaded.
Letter Number Punctuation Symbol Other Undefined
Code page 909
Code page 909 is another encoding for APL, differing from code page 907 in not including the underlined characters, assigning different codes to the APL characters which fall in the 0xB0–DF range, and replacing some of the C0 replacement graphics from code page 437 with alternative encodings for certain APL symbols. Differences from code page 437 are shaded.
Letter Number Punctuation Symbol Other Undefined
Code page 910
Code page 910 is similar to code page 909, but with fewer duplicate horizontal arrows, using the same C0 graphics as code page 437, and including some additional characters. Differences from code page 437 are shaded.
Letter Number Punctuation Symbol Other Undefined
Unicode
Most APL symbols are present in Unicode, in the Miscellaneous Technical range,[23] although some APL products may not yet feature Unicode, and some APL symbols may be unused or unavailable in a given vendor's implementation.
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. Entering APL characters still requires the use of either a specific input method editor or keyboard mapping, or of a specific touch interface. APL keyboard mappings are available for free for the most common operating systems, or can be obtained by adding the Unicode APL symbols to existing keyboard map.
Underscored alphabetic characters
Missing from Unicode are the traditional underscored alphabetic characters included in some of the APL code pages; their usage has been eliminated or deprecated in most APL implementations. These were produced on APL printing terminals by over-striking a straight capital letter with an underscore character. Some tables show them simulated with underlined and italic markup, not listing Unicode mappings.[3]
IBM assigns them GCGIDs as "LA480000" (which they name "A Line Below Capital/A Underscore (APL)"), "LB480000" ("B Line Below Capital/B Underscore (APL)") and so forth, under the "L" series used for Latin letters.[1] The use of an even number (48) rather than an odd number (47) is due to being uppercase: compare the use of SD110000 for a lone acute accent ´, LA110000 for the lowercase á, and LA120000 for the uppercase Á.[24]
Homologous uses of 47 are seen in the "SD" (diacritic) series GCGID SD470000 for "Line Below/Discontinous Underscore"[25]—i.e. macron below, distinct from the ASCII underscore which is SP090000 ("Underline/Continuous Underscore")[24]—and the "A" (Arabic letter) series GCGID AD470009 for the ḏāl,[26] for example. Unicode's Latin Extended Additional block includes the following capital "Line Below" characters with the macron below diacritic, for Semitic transcription:
- U+1E06 Ḇ LATIN CAPITAL LETTER B WITH LINE BELOW
- U+1E0E Ḏ LATIN CAPITAL LETTER D WITH LINE BELOW
- U+1E34 Ḵ LATIN CAPITAL LETTER K WITH LINE BELOW
- U+1E3A Ḻ LATIN CAPITAL LETTER L WITH LINE BELOW
- U+1E48 Ṉ LATIN CAPITAL LETTER N WITH LINE BELOW
- U+1E5E Ṟ LATIN CAPITAL LETTER R WITH LINE BELOW
- U+1E6E Ṯ LATIN CAPITAL LETTER T WITH LINE BELOW
- U+1E94 Ẕ LATIN CAPITAL LETTER Z WITH LINE BELOW
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.[3] Unicode's Mathematical Alphanumeric Symbols block includes italic characters for use in notations where they are contrastive with non-italic characters. Unicode also includes combining forms of the macron below and underscore in the Combining Diacritical Marks block; the characters above canonically decompose with the former:
- U+0331 ◌̱ COMBINING MACRON BELOW
- U+0332 ◌̲ COMBINING LOW LINE
Keyboard layout
Note the mnemonics associating an APL character with a letter: ? (question mark) on Q, ⋆ (power) on P, ρ (rho) on R, ⊥ (base value) on B, ⊤ (eNcode) on N, ∣ (modulus) on M and so on. 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. Also, decals have been produced for attachment to standard keyboards, either on the front of the keys or on the top of them.
Later IBM terminals, notably the IBM 3270 display stations, had an alternate keyboard arrangement which is the basis for some of the modern APL keyboard layouts in use today.
Further APL characters were available by overstriking one character with another. For example, the log symbol (⍟) was formed by overstriking ⇧ Shift+P with ⇧ Shift+O. This extended the graphic abilities of the earlier teleprinters, but made it more complex to correct errors and edit program lines.
New overstrikes were introduced by vendors as they produced versions of APL tailored to specific hardware, system features, file systems, and so on. Further, printing terminals and early APL cathode-ray terminals were able to display arbitrary overstrikes, but as personal computers rapidly replaced terminals as a data-entry device, APL character support became provided as an APL Character Generator ROM or a soft character set rendered by the display device. With the advent of the modern PC, APL characters were defined in specific fonts, eliminating the distinction between overstruck characters and standard characters.
Finally, the symbols were ratified in Unicode and given specific code points, with unambiguous interpretations, independently of the graphic font.
See also
Footnotes
- ^ a b c d Naming convention (which way around "up" and "down" are, and which way around "left" and "right" are) of tack characters differs between IBM and Unicode, and also between Unicode characters intended solely for APL versus those also intended for other applications.
- ^ a b c d e f g h i j k l m n o p q r s t u Documented mappings vary.[3][5][19][10]
- ^ a b c d Sharp extension.[5]
References
- ^ a b c "Graphic Escape APL2/TN - 138". IBM. GCSGID 00963.
- ^ a b c "Graphic Escape APL2/TN - 138 (chart)" (PDF). IBM. GCSGID 00963.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x Tachyon Software (2007-07-31). Code Page 00310: 3270 APL Graphic Escape.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x Cowan, John (2004-06-29). "ISO-IR-68 to Unicode". Unicode.org. Unicode, Inc. Retrieved 19 June 2017.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y "x3270 Character Set". x3270 Documentation. Archived from the original on 2018-11-10.
- ^ a b "Personal Computer". IBM. CPGID 00437.
- ^ a b c IBM. Code Page 00907 (PDF). Archived from the original (PDF) on 2017-08-03.
- ^ a b c IBM. Code Page 00909 (PDF). Archived from the original (PDF) on 2015-07-08.
- ^ a b c IBM. Code Page 00910 (PDF). Archived from the original (PDF) on 2015-07-08.
- ^ a b c d e f g h i j k l m n o "EBCDIC and ASCII Tables".
{{cite web}}:|archive-url=is malformed: timestamp (help) - ^ a b c d e IBM (1996) [1984]. "Code Page (CPGID) 00293: APL (USA)". REGISTRY, Graphic Character Sets and Code Pages.
- ^ a b c d Tachyon Software (2007-07-31). Code Page 00293: EBCDIC APL.
- ^ "IBM Simplified Chinese Graphic Character Set for Extended UNIX Code (EUC)" (PDF). IBM. 1994. C-H 3-3220-132 1994-06.
- ^ "CCSID 293 information document". Archived from the original on 2016-03-27.
- ^ Code Page CPGID 00293 (pdf) (PDF), IBM
- ^ a b IBM (1987). "Code Page (CPGID) 00310: Graphic Escape APL/TN". REGISTRY, Graphic Character Sets and Code Pages.
- ^ xlate - Transliterate Contents of Records, IBM Corporation, 2010 [1986], retrieved 2016-10-18
{{citation}}:|archive-url=is malformed: timestamp (help)CS1 maint: url-status (link) - ^ IBM. "Appendix G-1. EBCDIC control character definitions". IBM Globalization. Archived from the original on 2018-09-11.
- ^ a b Code Page CPGID 00310 (pdf) (PDF), IBM
- ^ a b Tachyon Software (2007-07-31). Code Page 00351: GDDM Default (USA).
- ^ "Code Page 00371" (PDF). IBM. Archived from the original (PDF) on 2015-07-08.
- ^ a b Standards Council of Canada (1983-06-01). APL Character Set for Workspace Interchange (PDF). ITSCJ/IPSJ. ISO-IR-68.
- ^ "The Unicode Standard 5.1 Code Charts: Technical Symbols U+2300-U+23FF" (PDF). Unicode Standard 5.1. Unicode Consortium. Archived (PDF) from the original on 2 October 2008. Retrieved October 12, 2008.
- ^ a b "Windows, Latin 1". IBM. CPGID 01252.
- ^ "OCR B". IBM. GCSGID 00969.
- ^ "Windows, Arabic (PDF)" (PDF). IBM. CPGID 01256.
- ^ A more up-to-date keyboard diagram, applicable for APL2 and other modern implementations, is available at WikensOnline Union APL large keyboard layout for Windows Archived March 10, 2012, at the Wayback Machine, actual photo + diagram here Archived April 3, 2015, at the Wayback Machine and NARS2000 APL keyboard layout here.
External links
- IBM code page 293 a.k.a. the APL code page on mainframe computers
- IBM code page 907 a.k.a. the APL ASCII code page
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