# Ontologies and schemas¶

## Tier 0¶

Raw data collections (“tier 0”) in the production system do not adhere to a fixed schema or ontology, but instead have a schema which is very close to the raw data. Modifications to field names tend to be quite basic, such as lowercase and removal of whitespace in favour of a single underscore.

## Tier 1¶

Processed data (“tier 1”) is intended for public consumption, using a common ontology. The convention we use is as follows:

• Field names are composed of up to three terms: a firstName, middleName and lastName
• Each term (e.g. firstName) is written in lowerCamelCase.
• firstName terms correspond to a restricted set of basic quantities.
• middleName terms correspond to a restricted set of modifiers (e.g. adjectives) which add nuance to the firstName term. Note, the special middleName term of is reserved as the default value in case no middleName is specified.
• lastName terms correspond to a restricted set of entity types.

Valid examples are date_start_project and title_of_project.

Tier 0 fields are implictly excluded from tier 1 if they are missing from the schema_transformation file. Tier 1 schema field names are applied via nesta.packages.decorator.schema_transform

## Tier 2¶

Although not-yet-implemented, the tier 2 schema is reserved for future graph ontologies. Don’t expect any changes any time soon!