# Tag Documents into Clusters

After indexing, you can tag documents into clusters of similar documents. Tagging can be useful for grouping duplicate documents together.

Use the index action `DRETAGDOCCLUSTERS`. This action takes the following parameters.

`TagField` | The full field name that contains document tags.
`MinScore` | The matching threshold to determine whether a document belongs to a cluster.
`TagSourceField` | The full field name to use as the source of the `TagField` value.
`MinID` | The first document ID to tag.
`MaxID` | The last document ID to tag.
`CheckSumField` | A reference field to use to determine whether a document is an exact match of another document.
`TaggedDBName` | The database which Content moves tagged documents to and retrieves tags from.
`RelevanceField` | The full field name that holds the relevance score of the document to its cluster.
`DatabaseMatch` | The names of databases that contain documents that you want to tag.
`CheckSumDBs` | The names of databases that you can checksum match against.
`ClusterDBs` | The names of databases that you can cluster against. This list includes `TaggedDBName` if specified.

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