> ## Documentation Index
> Fetch the complete documentation index at: https://docs.salvidia.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Evidence and audit trail
> What an assurance provider asks for, and the record Salvidia keeps so you can hand it over: data lineage, factor provenance, change history, and locked reporting periods.
A carbon number on its own is not worth much. What makes it usable in a tender, a sponsor pack, or a climate disclosure is the record sitting behind it: where each figure came from, which factor was applied, who changed what, and whether the period has been closed.
Salvidia is built to keep that record as a by-product of normal use, rather than something you assemble by hand at the end of the year.
Salvidia is not an assurance provider or auditor. We do not issue audit or assurance opinions. What we do is keep your inventory in a state where an assurance provider, a sponsor, or a customer's procurement team can check it.
## The four questions an assurer asks
Almost every review comes down to the same four questions. Each one maps to something the platform records.
Every calculated line traces back to the source record it came from, and that record traces back to the file it arrived in.
Factors are held in a versioned library with validity dates, a named publisher, and the region the factor applies to.
Recategorisations are logged with the previous value, the new value, who made the change, and when.
An assessment can be finalised, so the figures behind a published report do not drift afterwards.
## Data lineage
When data arrives from your accounting system, whether uploaded as a ledger file or synced from Xero, it is not flattened into a total. Each step is kept and linked to the next:
The upload is recorded with its file name, row count, and an integrity fingerprint, so the exact file behind an assessment can be identified later. Re-uploading the same file is detected rather than silently double counted.
Every row is staged as it appeared in the original file before any interpretation is applied.
Rows become transactions carrying date, description, amount, account code and name, supplier, and invoice reference, with a content fingerprint used to detect duplicates.
Each transaction is assigned an emission category and source. Automatic assignments carry a confidence value, so low-confidence items can be reviewed first.
Only then does a transaction become an emissions line with Scope 1, 2, and 3 splits and a calculated result, still linked back to the transaction it came from.
The practical effect is that any line in your results can be walked backwards to a row in a file your finance team recognises.
## Factor provenance
Calculations are only as defensible as the factors behind them. Salvidia's factor library is structured rather than hard-coded:
* **Versioned.** Factors carry validity dates and a current flag, so a prior year is calculated on the factors that applied at the time rather than today's.
* **Attributed.** Factors reference a registry of published sources, each recorded with its publisher, licence, and attribution text.
* **Regional.** Factors carry a country and region, and routing rules decide which library applies to a given organisation or event.
* **Described.** Each factor records its basis, the greenhouse gas warming set used, and a data quality rating.
See [Emission factors](/methodology/emission-factors-overview) for how factors are selected and applied.
## Change history
Categorisation is where judgement enters a carbon inventory, so it is the part most worth recording. When a transaction moves from one emission category to another, Salvidia writes a log entry holding the previous category and source, the new category and source, the confidence before and after, who made the change, and the reason given.
That log is what turns "we reclassified some freight" into something a reviewer can actually inspect.
## Evidence references and calculation basis
Activity records carry two fields that exist purely for review:
* **Evidence reference.** The invoice, meter read, or supporting document a figure came from.
* **Calculation basis.** Whether the line was computed from activity data, carried across from a prior period, or estimated.
An estimate is labelled as an estimate. Nothing in Salvidia presents a modelled figure as a measured one.
## Locking a reporting period
An assessment can be finalised once its numbers are settled. Finalising records the moment the inventory was closed and separates a published figure from a working one, so a report you have already sent to a sponsor or a customer keeps saying what it said when you sent it.
## What you can hand over
Every data table in an assessment exports to CSV, covering the activity records, their Scope 1, 2, and 3 splits, the calculated result, and, where the table supports it, the evidence reference and calculation basis. You can export a whole table or only the rows you have selected.
That gives a reviewer three things to work with: the underlying activity data, the calculated result for each line, and the reference back to your own supporting documents.
If your assurance provider has a required workbook format, send it through. Mapping an export into a specific template is something we can help with directly.
## Where to go next
* [How emissions are calculated](/methodology/how-emissions-are-calculated)
* [Emission factors](/methodology/emission-factors-overview)
* [Standards and frameworks](/methodology/standards-and-frameworks)
* [Working with data](/platform/working-with-data)