UiPath UI libraries support centralized management and reuse of application UI elements through the Object Repository. They allow automation developers to maintain consistent UI descriptors across multiple projects and reduce duplicated selector definitions.

Option B correctly identifies the documented versioning constraint: a UI library may contain multiple applications, but only one version of a particular application can exist within that library at a time.

This restriction is important for dependency management. When a UI library is published as a package and installed into dependent Studio projects, the application descriptors become available for reuse.

Maintaining a single application version within the library establishes a consistent representation of its screens and UI elements.

When an application changes, developers should update the relevant library definitions while preserving reusable UI elements and stable identifiers where appropriate. Publishing an updated library package then allows consuming projects to upgrade through their dependency management process.

Option A incorrectly requires duplication across screens. Option C introduces an unsupported requirement that unrelated applications share identical version numbers. Option D incorrectly restricts applications to a single screen.

The correct architectural practice is to manage application definitions centrally, retain stable UI element references where possible, and apply controlled library version upgrades across dependent automation projects.

Official UiPath Reference(s): Studio User Guide — Reusing objects and UI libraries; Publish a UI library; Load UI libraries in projects.