Units, symbols and facts

A narrator reading "accelerating at 1 g" says "one gram" — and viewers notice. On screen, "1G" reads as giga, "5kgs" as careless and "KMPH" as wrong. So every text an episode holds goes through a units guard that writes units and symbols as the standards do — the SI Brochure and NIST's guide, with the non-SI units NIST accepts — and every fact goes through the critic before anything is posted.

What the guard checks#

The guard reads two kinds of text, by different rules:

• What is said — every line of the narration. It must hold no symbol a voice could misread: units are said in words.
• What is shown — the captions, the words the episode's own code draws (the title card, the data chip and its label, the end card), and everything posted with the video: the title, the description, the Facebook caption, the tags and the hashtags. These use the standard's symbols, exactly.

The rules#

Said#

• Units in words, in British spelling, the numbers as figures: "1 gee" (or "1 times Earth's gravity") for 1 g, "9.81 metres per second squared", "240 kilometres per hour", "20 degrees Celsius", "a 5 kilogram ball".
• Other signs in words too: "3 × 10⁸" is "3 times 10 to the power of 8", "~" is "about", "±" is "plus or minus", "3x" is "3 times".
• A gram is only ever a mass. "Accelerating at one gram" is the mistake itself, in words.

Shown#

• The standard's symbols, with their case whatever the text around them: kg, km, m, s, ms, K for kelvin and k for kilo, M for mega, G for giga, W, kW, MW, kWh, Hz, kHz, MHz, GHz, N, Pa, kPa, J, eV, MeV, L, mL, dB, mAh, Ω, and µ for micro. A title in capitals still writes "km/h", not "KM/H".
• A space between a number and its unit: "5 kg", "20 °C", "240 km/h" — but "30°" for an angle. Japanese, Chinese, Korean and Thai set no space, as their typography does. The guard sets the space for symbols of two or more letters ("5km" becomes "5 km"); a one-letter symbol such as "5m" or "10s" is left as written, so the writer spaces it.
• Never plural, never a full stop after the symbol: "kg", not "kgs"; "lb", not "lbs"; "min", not "mins"; "s", not "secs"; "h", not "hrs".
• "K", never "°K"; kelvins, never "degrees kelvin". "km/h", never "kmph", "kph" or "km/hr". "µm", never "um".
• Powers as superscripts: "m/s²", "m³", "3 × 10⁸ m/s"; "6e-11" becomes "6 × 10⁻¹¹". Text the episode draws keeps "10^8" for other powers, because its typeface has only ² and ³.
• A bare C or F in a sentence about heat becomes °C or °F.
• mph, ft, mi, lb, psi, °F, AU and light-years are all fine.
• A data chip draws its label in capitals, so a unit belongs in the chip's value, never its label: "SPEED" · "240 km/h", not "SPEED (km/h)".

Gravity#

• Never "1g", "1G" or "1 G" for g-force. On screen, "1 g" only where the same sentence says what it is: "1 g · Earth's gravity", "9 g-force", "1× Earth's gravity", "9.8 m/s²".
• Capital G is only the gravitational constant, or giga.
• A mass is a mass: "a 10 g sock" and "5 g of sugar" are right as they are.

Not units#

These are never touched: 5G, 4G LTE, 4K, 1080p, F1, B-52, K2, V8, M4, T-rex, G-Shock, Model 3, colour codes, version numbers, times of day (10:30), decades (the 1920s) and money ($5m). "3x faster" is left as it is on screen; said, it becomes "3 times faster".

What is fixed for you, and what fails#

Most problems are typography, and the right form is certain. A few only the writer can settle, and those are fatal:

• a "g" with nothing around it to say whether it is g-force or grams;
• a symbol that means two things, wherever it appears — "5 mw" (milliwatts or megawatts?), "mb" (megabytes, megabits or millibars), "gb" and "tb" (bytes or bits);
• "kt" in the narration when nothing around it says kilotons or knots: "a 50 kt blast" is said as kilotons and "winds of 50 kt" as knots, but "it was 50 kt" fails. On screen, "kt" is left as written.

A failure reads like this in the quality report, with its fix:

Units: narration line 7 says “1 g”: say “1 gee” for g-force or “1 gram” for a mass, in words
Units: caption at 12.5 s “Pulls 9G”: “9G” reads as giga or the gravitational constant: write “9 g-force” or “9× Earth's gravity”
Units: caption at 42.0 s “Top speed / 240kmph”: “240kmph” → “240 km/h”

Episodes are written to these rules in the first place: the writer's brief carries them, and the voice flags a symbol as each line is written, so the gate rarely has anything left to fail.

Where it applies#

How facts are kept honest#

Units are one part of getting the facts right. The rest is a chain, from the topic to the post:

1. Topics carry their facts. Each topic in a channel's backlog is planned with three to five key facts with real numbers, one to three real sources, and two to four surprising facts, each with a number and its source — only what well-established sources support: agencies, manufacturers' published specifications, peer-reviewed science, standard references.
2. The writer uses only what it can stand behind. It writes only well-established numbers it is confident of, rounds sensibly, and leaves out any number it is not sure of. Each episode's record lists its facts with their sources, and its description carries a "Sources:" line — the quality report notes a missing one.
3. The critic checks every word. Every caption, every narration line and the title must be correct and not misleading, every number right; a unit a viewer would misread counts as a factual error. A factual error or a misleading claim blocks the episode: it goes back to be fixed, and is held if it cannot be.
4. You can check them first. With storyboard approval, each beat of the plan lists the facts it relies on, with their sources, before anything is made.
5. Films are researched before they are written. A film's plan is researched and fact-checked before its script, and its acts are reviewed one by one.
6. Products say only what is sourced. A product channel says only the claims its brief sourced from the product's page, and the critic is asked whether it claims anything more.
7. Translations keep the numbers. A translation keeps the original's meaning and numbers exactly; their facts were checked when the original passed.
8. The record keeps it all. The originality record of an episode lists its facts and sources and what the critic's fact check said — for an appeal, or for your own files.

Limits and good to know#

• The guard is code, not a model: the same text always gets the same verdict, and a text with no unit problem is left exactly as it was.
• It judges how a unit is written, not whether a number is true. That is the critic's job, and the topic's sources'.
• Only English narration has its symbols said in words for you. In another language the narrator reads the line as written, so the writer is asked to write each unit out in the language itself.

Troubleshooting#

Related#

• The quality gates and the critic
• Episodes — what an episode holds
• Studio: one inbox for every comment — replies and their checks