--- title: "How to Review a Monomer's Version History" slug: "how-to-review-a-monomer-version-history" status: "update" updated: 2026-11-03T16:08:26Z published: 2026-11-03T16:08:26Z canonical: "docs.discngine.com/how-to-review-a-monomer-version-history" --- > ## Documentation Index > Fetch the complete documentation index at: https://docs.discngine.com/llms.txt > Use this file to discover all available pages before exploring further. # How to Review a Monomer's Version History This guide shows how to find out what changed on a monomer, who changed it and when, and how to put a deleted monomer back. It continues the example of [How to Create or Edit a Monomer](/public/docs/how-to-create-or-edit-a-monomer), where `MeNle` had its C-terminal cap corrected and `Deg` was registered. **Prerequisites**: the **Administrator** role in Biotoolkit Monomers. The **Version history** entry appears in the navigation menu only for Administrators. ## Step 1: Open the Version history In the navigation menu, click **Version history**, the clock icon. Four cards summarise the page: the changes of the **last 30 days**, the monomer **most edited**, how many deletions are waiting **to revive**, and the **last change**. Below them, the report lists one row per archived state, newest first. Each row is a version of a monomer that is no longer current, either because an edit superseded it or because the monomer was deleted. ![The Version history filtered on MeNle: the four cards, the Show chips, then its deletion with the Revive button on top and, below, the edit whose What changed reads R-groups, with the drawings before and after](https://cdn.document360.io/dde9293e-c107-4b3e-9774-9c9c296ed970/Images/Documentation/biotoolkit-monomer-service-version-history.png?sv=2026-02-06&spr=https&st=2026-11-11T07%3A53%3A50Z&se=2026-11-11T08%3A53%3A50Z&sr=c&sp=r&sig=3h%2Fzm6aIH%2FeZ6UfFZX%2FTD%2B3O94Kz4ozr7bsOI%2FiMAgU%3D) The default view shows: | Column | Meaning | | --- | --- | | **Before** / **After** | The structure as it was, and the structure that replaced it. **After** is empty for a deletion. Click a drawing to open it full size in the structure viewer. | | **Monomer** | The symbol and the name of the archived state. | | **Version** | For an edit, the number before and after, as `1 → 2`; for a deletion, the number the monomer had. | | **What happened** | A chip: `Edited`, `Deleted`, or `Deleted, since revived`. | | **What changed** | For an edit, one tag per field that differs: `symbol`, `name`, `polymer type`, `monomer type`, `natural analog`, `structure`, `R-groups`. | | **When**, **By** | When the state was archived, and the account that did it. | | **Revive** | Present on a deletion that has not been revived. | The **R groups** and **R groups after** columns, as `R1: H, R2: OH`, and the **SMILES** and **SMILES after** columns for a text comparison, are available from the report's **Actions** menu, under **Columns**. The **Show** chips above the report narrow the list: **All**, **Edits**, **Deletions**, and **To revive**, which keeps only the deletions that can still be undone. Each chip carries its count, and the **To revive** card selects the chip of the same name. ## Step 2: Read an edit Type `MeNle` in the search box and press Enter: the report keeps only the rows of that monomer, newest first. The row of the cap correction reads: - **What happened**: `Edited`. **What changed**: `R-groups`. - **Version**: `1 → 2`. The wrong state was version 1; the live monomer is version 2. - **R groups**: `R1: H, R2: H`. **R groups after**: `R1: H, R2: OH`, once the two columns are shown. A deleted monomer keeps its whole history: the screenshot above shows the deletion of `MeNle` on top, with its **Revive** button, and below it the edit that preceded it. The same list, limited to one monomer, is in the **Audit** tab of its dialog. Had the structure been changed as well, **What changed** would carry the tags `structure` and `R-groups`, and the **Before** and **After** drawings would differ. Only **material** changes appear here: symbol, polymer type, monomer type, natural analog, structure and R groups. A change of name or author, or a regenerated drawing, does not create a version. See [Versioning and Deletion](/public/docs/monomer-versioning-and-deletion). ## Step 3: Revive a deleted monomer Suppose a curator deleted `Deg` by mistake. Select the **To revive** chip, find the row, and click **Revive**. The **Revive monomer** dialog asks **Put this monomer back?**: confirm with **Revive**. Reviving is also the answer when a curator is told, on registering a symbol, that it *corresponds to 1 deleted monomer*: see [Versioning and Deletion](/public/docs/monomer-versioning-and-deletion). ![The Version history on the To revive chip, with the Revive button on each row and the "Put this monomer back?" confirmation open](https://cdn.document360.io/dde9293e-c107-4b3e-9774-9c9c296ed970/Images/Documentation/biotoolkit-monomer-service-version-history-revive.png?sv=2026-02-06&spr=https&st=2026-11-11T07%3A53%3A50Z&se=2026-11-11T08%3A53%3A50Z&sr=c&sp=r&sig=3h%2Fzm6aIH%2FeZ6UfFZX%2FTD%2B3O94Kz4ozr7bsOI%2FiMAgU%3D) The monomer returns to the library under its original identifier, with a new version number, its original creation date, and the metadata and monomer-set memberships it had. The confirmation reads: ``` Monomer "Deg" is back, with 0 set membership(s) and 0 metadata row(s) restored. ``` If a monomer set it belonged to has been deleted in the meantime, the membership cannot be restored and the message says how many were skipped. The row then reads `Deleted, since revived` and loses its **Revive** button. A revive is refused, with the reason, when: - a live monomer now holds the same symbol, name or structure for that polymer type. Rename or remove that monomer first, or leave the version archived; - the monomer is public. Public reference data is maintained by Discngine and is never deleted through the application; - the monomer was already revived, or its most recent archived state is an edit rather than a deletion. ## What the log cannot tell you - **The person behind changes made before the 2026.11.02 release.** Edits, imports and deletions are attributed to the user who made them, but changes recorded before that release read `System` in **By**: they were applied by the Biotoolkit service, which did not record the user then. For an import of that period, the **Import history** on the Import monomers page records who uploaded the file. - **Cosmetic changes.** Redrawing the same molecule, or renaming it, leaves no trace here.