> For the complete documentation index, see [llms.txt](https://docs.geosamples.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.geosamples.org/metadata-schema/readme.md).

# Overview & data model

This section covers SESAR sample metadata: requirements, the database schema, legacy migrations, and external crosswalks. Controlled term lists are in **Vocabularies**; programmatic create/update is in **API**.

| If you want to…                            | Start here                                                                                                               |
| ------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------ |
| See what is required to register           | [Field requirements](/metadata-schema/field-requirements.md)                                                             |
| Inspect tables, columns, and ER diagrams   | [Database schema](/metadata-schema/database-schema.md)                                                                   |
| Map SESAR 1.0 fields to the current schema | [Field crosswalk (old → new)](/metadata-schema/migration-from-the-legacy-schema/field-crosswalk-old-greater-than-new.md) |
| See which vocabulary lists were renamed    | [Renamed vocabularies](/metadata-schema/migration-from-the-legacy-schema/renamed-vocabularies.md)                        |
| Map old sample types to object type        | [Sample type to object type](/metadata-schema/migration-from-the-legacy-schema/sample-type-to-object-type.md)            |
| Map old classification to material type    | [Classification to material type](/metadata-schema/migration-from-the-legacy-schema/classification-to-material-type.md)  |
| See how SESAR fills DataCite DOI records   | [DataCite](/metadata-schema/crosswalks/datacite.md)                                                                      |
| Crosswalk to Darwin Core or iSamples       | [Darwin Core](/metadata-schema/crosswalks/darwin-core.md), [iSamples](/metadata-schema/crosswalks/isamples.md)           |


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