> For the complete documentation index, see [llms.txt](https://docs.libnova.com/libsafe-advanced-preservation-administrator-manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.libnova.com/libsafe-advanced-preservation-administrator-manual/metadata-collision-groups/unicity-metadata-collision-groups.md).

# Unicity metadata collision groups

A Unicity metadata collision group consists of a set of metadata descriptors that establish that two objects with the same value in the specified descriptor are really the same object. The feature of this collision group is not to allow any two objects with the same set of metadata, hence **LIBSAFE** will reject the object, which will cause the ingestion job to fail.

The main screen lists the unicity metadata collision groups, showing name, description, access to the detail, editing and elimination.

{% hint style="info" %}
**Note**: as a general rule, it is recommended not to configure unicity metadata collision groups. These collision groups are not compatible with certain functionalities, like for instance with format evolution.
{% endhint %}

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