# Reference quantities and units

## Definitions

Distinguish three quantity levels: the dataset's reference product quantity, elementary flow quantities in cumulative
LCI, and LCIA results. Their units are respectively reference product units, elementary flow units and category
indicator units. These quantities and units are not interchangeable.

The standard [reference flow](/en/data-reference/glossary#standard-terms) and this site's reference product quantity field
are different concepts. See [model catalog column definitions](/en/resources/file-definitions#database-overview) for field values and
preservation of original quantities.

## Fields

The table links definitions in the two representations. XLSX column names are not API field names.

| Quantity level              | XLSX definition                                                                    | API definition                                                                        |
| --------------------------- | ---------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------- |
| Reference product           | [Reference Product Amount / Unit](/en/resources/file-definitions#database-overview)              | [referenceProduct.amount / referenceProduct.unit](/en/data-access/query-api#lookup-fields) |
| Cumulative elementary flows | Not included in public catalog files; see [public scope](/en/resources/file-definitions#release) | [Cumulative LCI result fields](/en/data-access/query-api#result-fields)                    |
| LCIA results                | Not included in public catalog files; see [public scope](/en/resources/file-definitions#release) | [LCIA result fields](/en/data-access/query-api#result-fields)                              |

## Missing values

See [Known gaps](/en/resources/file-definitions#known-gaps) for field coverage in release catalogs. The API's cumulative LCI unit
convention is documented under [result fields](/en/data-access/query-api#result-fields). Read missing values according to the
applicable representation; do not interpret them as zero.