Concepts
Releases, activation and reproducible years
Publishers reissue their factors every year. Slate treats each issue as a fixed release, picks one by the date of each activity, and locks a reporting year to the release it was first calculated with.
On this page you'll learn
- How a release is chosen for a record
- Why importing a release doesn't change anything until it's activated
- How a published year stays reproducible
- Release
- One immutable published edition, stored with its file's SHA-256
- Selected by
- Publisher, edition, and the record's transaction date
- Pinned
- Per reporting year, publisher and edition
One date, one release
Each release has a validity window. EPA's 2022 Hub covers 1 January to 31 December 2022; only the newest is open-ended. Windows within an edition never overlap, so a transaction date selects exactly one release, and the answer can't depend on sort order.
Some publishers run several catalogues at once. EPA's main Hub and its waste table are separate editions, and IPCC has a dozen. Each edition declares which kinds of activity it answers, so a stationary record can never be priced from the waste table.
Import is not activation
- 1
Dry run
The new file is checked: header layout, units, the expected number of rows and of blank cells.
- 2
Import
The release is loaded but inactive. Nothing is priced from it yet.
- 3
Compare
A diff against the previous release shows what moved, the in-app equivalent of DEFRA's major changes report.
- 4
Activate
Only after review. Activation retires an overlapping release of the same edition and never touches a pinned year.
Note
Re-importing different content under an existing version is refused. A corrected file has to come in as a new revision (for example 2027-r2), so the original is never changed underneath figures that used it.
Reproducible reporting years
The first successful calculation in a reporting year creates a pin for that year, publisher and edition. Recalculating the year later uses the pinned release even if a newer one has been activated, so a published report gives the same answer next year.
Recalculating an old year still needs that year's release to exist. That is why Slate holds EPA's back catalogue from 2020: without it, a 2022 record would find no release covering its date.
Blank is never zero
A cell the publisher left empty is stored as missing, never as 0. DEFRA reissued its 2026 file because blanks had been published as zeros; a zero factor removes real emissions while looking like an answer. The expected blank count (1,705 for DEFRA 2026) is checked on every import.