This feature covers **global** sub-types, managed by instance administrators and available to every project. Project-owned sub-types, the project permission, in-project visibility isolation, and promotion to global are a separate, larger feature (to be creatd)

**As an** OpenProject  administrator
**I want to** create and manage global sub-types under an existing work package type
**so that** I can offer instance-wide variations of a type that present as the parent but can behave differently.

## Acceptance criteria

* I can create a global sub-type under any root Begin of the insertiontypeEnd of the insertion Begin of the deletion type. _(F0-C1, F0-C4)_End of the deletion

* A sub-type cannot itself have sub-types. The application enforces a single Begin of the insertionlevelEnd of the insertion Begin of the deletion level. _(F0-C1)_End of the deletion

* A sub-type cannot be its own parent, and standard types cannot be sub-typed or Begin of the insertionre-parentedEnd of the insertion Begin of the deletion re-parented. _(F0-C1)_End of the deletion

* A new sub-type Begin of the insertionis independent except forEnd of the insertion Begin of the deletion starts with every aspect (workflow, form configuration, settings) linked toEnd of the deletion its Begin of the insertionname 

End of the insertion Begin of the deletion parent, so it behaves exactly like the parent until I change it. _(F0-C1, F0-C2)_

End of the deletion * Begin of the insertionRelated features  ##FND-101  ##FND-102

* End of the insertion A sub-type appears in administration nested under its parent and labelled with its composite name ("Bug: Begin of the insertionHardware")End of the insertion Begin of the deletion Hardware"). _(F0-C3, F0-C4)_End of the deletion

* A sub-type inherits its core settings from the parent and cannot edit them: color, `is_milestone`, `is_in_roadmap`, and `is_default` are shown read-only and always follow the Begin of the insertionparentEnd of the insertion Begin of the deletion parent. _(F0-C3)_End of the deletion

* A sub-type carries only its own variant label, used in administration, Begin of the deletion hover,End of the deletion and the composite Begin of the deletion name; the displayed typeEnd of the deletion name Begin of the insertion

* A sub-type's display name isEnd of the insertion always Begin of the deletion resolves toEnd of the deletion the Begin of the insertionparent nameEnd of the insertion Begin of the deletion parent. _(F0-C3)_End of the deletion

* The system prevents creating a cyclic dependency between reuse Begin of the insertionsourcesEnd of the insertion Begin of the deletion sources. _(F0-C2)_End of the deletion

* The entire capability is hidden and inert unless the `work_package_subtypes` feature flag is Begin of the insertionenabledEnd of the insertion Begin of the deletion enabled. _(F0-C0)_End of the deletion


## Permissions and visibility considerations

* **To whom is this feature visible?** Instance administrators (the existing global type administration).

* **When is it not visible?** Feature Flag turned off, all non-admin users.


## Translation considerations

<figure class="table op-uc-figure_align-center op-uc-figure"><table class="op-uc-table"><thead class="op-uc-table--head"><tr class="op-uc-table--row"><th class="op-uc-table--cell op-uc-table--cell_head"><p class="op-uc-p">English</p></th><th class="op-uc-table--cell op-uc-table--cell_head"><p Begin of the insertionclass="op-uc-p">German</p></th><thEnd of the insertion Begin of the deletion class="op-uc-p">German (verify)</p></th><thEnd of the deletion class="op-uc-table--cell op-uc-table--cell_head"><p class="op-uc-p">French (verify)</p></th><th class="op-uc-table--cell op-uc-table--cell_head"><p class="op-uc-p">Spanish (verify)</p></th></tr></thead><tbody><tr class="op-uc-table--row"><td class="op-uc-table--cell"><p class="op-uc-p">Sub-type</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Untertyp</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Sous-type</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Subtipo</p></td></tr><tr class="op-uc-table--row"><td class="op-uc-table--cell"><p class="op-uc-p">Parent type</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Übergeordneter Typ</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Type parent</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Tipo principal</p></td></tr><tr class="op-uc-table--row"><td class="op-uc-table--cell"><p class="op-uc-p">Source type</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Quelltyp</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Type source</p></td><td class="op-uc-table--cell"><p class="op-uc-p">Tipo de origen</p></td></tr></tbody></table></figure>

* Document the hierarchical name (`"TYPE: SUBTYPE"`) used in admin, possibly on hover, and API.


## Out of scope

* Project-owned sub-types, the `:manage_subtypes` project permission, in-project visibility isolation, and promotion to global (Feature 8).

* Per-aspect reuse behavior beyond the default parent links (Features 1, 2, 3).

* Project activation and the one-per-family rule (Feature 5).

* Display routing across the product (Feature 4).