# Sub File Indexes

Documents in IDOL Server can represent sub-files. In these documents, the `AUTN_IDENTIFIER` field contains the identifier of the container file.

To retrieve a sub-file from a repository, a connector must retrieve the container file and send it to KeyView so that the sub-file can be extracted. So that KeyView can extract the correct sub-file, the identifier must include a sub-file index.

When CFS indexes documents into IDOL Server, sub-file indexes are automatically written to the `SubFileIndexCSV` document field. For example:

    SubFileIndexCSV="1"

NOTE: Your connector must be configured with `EnableExtraction=true`. The connector's `KeyviewDirectory` parameter must also be set.

The sub-file index in this example (`1`) indicates that the document represents the second file in the container (the sub-files are indexed from 0).

Container files can contain other container files (for example an e-mail message file could contain ZIP file attachments, containing further sub-files). In this case, the sub-file index might include more than one level:

    SubFileIndexCSV="2,6"

A sub-file index of `2,6` indicates that the document represents the seventh file in the third container, in the original container file.

When an action is sent to a connector to retrieve sub-files, the sub-file index must be appended to the identifier of the container. For example:

    PGlkIHM9Ik15VGFzazEiIHI9Imh0dHA6Ly9teXNlcnZlcjo0NTY3L2RvYy9fdnhzd
    2RmZ3VoamtuYmlvX2VhcnljcXp0XyI+PHAgbj0iU0VSVklDRVVSTCIgdj0iaHR0cD
    ovL215c2VydmVyOjQ1Njcvc2VydmljZSIvPjxwIG49IkRPQ0lEIiB2PSJfdnhzd2R
    mZ3VoamtuYmlvX2VhcnljcXp0XyIvPjwvaWQ+|2.6

NOTE: Where sub-file indexes have multiple levels (for example `SubFileIndexCSV="2,6"`, the comma must be replaced by a period).

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