Blog / Deep Dives
Deep Dives
One character, the long version — where it came from, what it actually means, and the arguments people have had about it.
≤ Less-than Or Equal To Less Than Or Equal To Pierre Bouguer put a bar under the angle in 1734, and he drew two of them: his mark was ≦, with a double horizontal rule. The single-bar form now treated as standard is a later simplification, and…∵ Because The inverted twin of therefore, and the newer of the two by convention rather than by invention. Johann Rahn's Teutsche Algebra of 1659 brought the three-dot triangle into algebra, but early writers…∖ Set Minus Set minus, reverse solidus operator, backslash — one drawing, three codepoints, and the differences are not aesthetic. A ∖ B is a set difference — the elements of A that are not in B — and a maths…∀ For All It is a letter standing on its head. Gerhard Gentzen introduced ∀ in 1935 — an inverted A, by analogy with Peano's already-established ∃ — which means the universal quantifier had been in use for…➡ Black Rightwards Arrow Black Right Arrow The black arrow set is scattered across the standard, and this character is the reason. Zapf Dingbats had a rightwards black arrow, so Unicode inherited it in 1993 at U+27A1, inside the Dingbats…⇐ Leftwards Double Arrow Left Double Arrow In a proof it reads backwards: A ⇐ B says B implies A, so the eye has to run the sentence right to left. That reversal is exactly why it sits beside the rightwards double arrow — it lets an author…₸ Tenge Sign Three cross-references in the standard, and not one of them is a currency: U+2351 APL FUNCTIONAL SYMBOL UP TACK OVERBAR, U+2564 BOX DRAWINGS DOWN SINGLE AND HORIZONTAL DOUBLE, and U+3012 POSTAL MARK…₧ Peseta Sign Its reach had almost nothing to do with Spain. IBM put the peseta sign into code page 437, the character set burned into the original PC's display hardware, at byte 0x9E — so every DOS machine on…₣ French Franc Sign An F with a crossbar — and Unicode's own cross-reference points at a character that looks identical to it: U+A798 LATIN CAPITAL LETTER F WITH STROKE, a letter used in African orthographies. Same…₠ Euro-currency Sign Unicode almost never raises its voice, and here it does. The annotation attached to this character reads "historical character; this is NOT the euro!" — exclamation mark and all. The mark was drawn…❣️ Heart Exclamation Read the full Unicode name and the design gives itself up: HEAVY HEART EXCLAMATION MARK ORNAMENT. This is not a heart, it is an exclamation mark — the heart takes the place of the mark's upper stroke…🧠 Brain The 2010 emoji intake came into Unicode largely from the Japanese carrier sets. This one did not: Unicode's EmojiSources file, which records the Shift-JIS codes the DoCoMo, KDDI and SoftBank symbol…💫 Dizzy The name is the whole argument. Unicode calls this DIZZY SYMBOL, and lists its aliases as "circling stars" and "squeans" — the second being the cartoonist Mort Walker's coinage, from his glossary of…💚 Green Heart Colour is the only thing separating it from the rest of the set, and colour turns out to carry a great deal. In English the green heart has attached itself to environmental and plant-based posts, to…💓 Beating Heart All three Japanese carriers had this one. Unicode's EmojiSources mapping lists a DoCoMo code, a KDDI code and a SoftBank code against U+1F493 — 0xF992, 0xF479 and 0xF9C7 — so it entered the standard…🌠 Shooting Star It draws a place, not a mark. The usual rendering is a slice of night sky with a streak across it, background and all, which makes it useless anywhere a star or a glowing star would do — dropped into…✡ Star Of David It reached Unicode by an odd route: not as a religious symbol but as a printer's ornament. The Dingbats block is essentially ITC Zapf Dingbats — Hermann Zapf's 1978 symbol font, the one Apple's…↕ Up Down Arrow Two heads, one shaft, and a different job from the single arrows on either side of it. Unicode files ↑ and ↓ as Sm, mathematical operators; this one is So, an ordinary symbol, because it does not…↓ Downwards Arrow Down Arrow Its general category is Sm — a mathematical operator, not a picture — and that is the clue to what it was encoded for. Chemistry uses it to mark a precipitate falling out of solution. Phonetics uses…⁎ Low Asterisk Set it beside the ASCII asterisk and the difference is vertical and nothing else: this one sits down on the baseline rather than up at the top of the line, where a footnote marker normally rides. The…💛 One of the five colours the emoji keyboard started with Twelve named-colour hearts exist today. Five of them, this one included, arrived together in the first emoji release; the newest three are fifteen years younger.❤️ A 1993 printer's ornament, still asking for permission to be red Every other heart on the emoji keyboard is a heart. This one is a Dingbats character from Unicode 1.1 that only turns red when a variation selector tells it to.💜 A colour word that was cheap in 2010 and expensive by 2022 U+1F49C got the unqualified word purple. Later hearts had to settle for light blue and grey, because a Unicode name can never be reassigned.❤️🔥 Four codepoints, one picture, and two ways to write it wrong Heart on fire is a joined sequence, not a character. Unicode lists both a fully qualified form and an unqualified one, and the difference is a single invisible codepoint.