Words we use

What the words mean

The names of the bodies, documents and satellites behind our figures, and the few words of our own, in plain terms. Pages link here the first time they use one.

Who publishes

Government Gazette, notice, R. 8129: The government’s official paper. A law, price or rule takes effect when it is printed there. Each item in it is a notice, and “R. 8129” or “No. 8129” is the notice’s number.
GPW: The Government Printing Works, which prints the Gazette and puts it online.
NERSA: The National Energy Regulator of South Africa. Every year it approves each municipality’s electricity prices.
DWS: The Department of Water and Sanitation. It publishes the weekly dam levels and rates drinking water and sewage works.
MDB: The Municipal Demarcation Board, which draws the boundaries of municipalities and wards.
Blue Drop, Green Drop, No Drop: The department’s ratings of drinking water (Blue Drop), sewage works (Green Drop) and water lost through leaks and unpaid use (No Drop).

Money and prices

Repo rate, prime: The repo rate is what the Reserve Bank charges banks. Prime is what banks charge their best customers; it is 3.5 points above the repo rate. Most home loans are priced from prime.
Prescribed rate: The interest rate the law sets for a debt where no rate was agreed, such as an unpaid court judgment.
NCA: The National Credit Act: the law that caps what lenders may charge.
Fuel zone, Zone 9C: Petrol is priced by zone. The coast is zone 1A; inland zones pay more because the fuel has further to travel. Gauteng is zone 9C.
Magisterial district: The area a magistrate’s court serves. Treasury’s list gives each one a fuel zone, so your zone comes from your magisterial district.

Electricity

kWh, units: One unit of electricity. A geyser element uses about 3 units in an hour of heating.
60 A single-phase: The size of your electricity supply. Most homes have 60 amp, single-phase. Your main switch or your bill says which you have.
SSEG: Small-scale embedded generation: rooftop solar that can feed power back into the grid.

From space and weather models

Greenness score (NDVI): A score for how green the land looks from space, from 0 (bare ground) to about 0.9 (thick green growth). We compare each month with the usual for that month.
Drought score (SPI, SPEI), “steps from normal”: A score for how unusual the rain has been: 0 is normal, −1 is dry, −2 is very dry, and +1 or more is wetter than usual. SPEI also counts water lost to evaporation.
Weather model (ERA5-Land, ERA5-Drought, reanalysis): A European weather model that estimates rain and temperature everywhere, every day, from past observations. It is an estimate for an area of about 9 km, not a reading from a weather station.
Air model (CAMS), “column”, µg/m³: The European air-quality model. “Column” is all the gas in the air above you, which is what satellites see. µg/m³ is the amount in the air you breathe, in millionths of a gram per cubic metre.
Land surface temperature: How hot the ground is (roofs, roads, soil), measured from space. It is hotter than the air on a sunny day.
Landsat, Sentinel-2, Sentinel-1, Sentinel-3, VIIRS, FIRMS, S-NPP, NOAA-20: Earth-observation satellites, American and European, and NASA’s fire-spotting service. We name them in the credits.
CLMS, GHSL, GHS-POP, WorldPop, WorldCover, JRC, WOfS, GLO-30, Digital Earth Africa: Names of open datasets made from satellite data by European, African and university groups. We name them in the credits.
Striped (hatched) areas: On our maps, stripes mean we have no data there.

Our own words

Release: A dated copy of a dataset that is never edited afterwards. A new price or a correction is a new release; the old one stays readable. The one exception is on the trust page.
Fingerprint (SHA-256): 64 characters worked out from a file. Change one character of the file and the fingerprint changes, so you can check nothing was altered. How to check one.
Figure, record: A figure is one number we publish, with its source and date. A record is how a figure is stored in our data; the API and the docs use that word.
Early access: Open to everyone, and may still change.
CC BY 4.0, ODbL: Open licences. You may use the data freely if you credit the source; ODbL also asks that a database you build from it stays open. Each dataset page says which applies.
UM-317 and other codes: Our own catalogue numbers for datasets. You only need them in the API.
DCAT, Parquet, JSON-LD, MCP, webhook: Formats and connections for software developers. They are explained in the docs.

A word missing? Write to hello@unmapped.co.za.