Importance of Workflow Enforcement on Tridion Items:
When a tridion item is updated outside of the workflow or a new item created, item was set to approval status 'undefined'. With this 'undefined' approval status there was no restriction on publishing those items at all, means the item (content/template) which was yet to be approved by workflow process could be published.
To make sure any unaudited item (content/template) doesn't get published. Tridion provides OOB functionality to Enforce Workflow on Components and Templates.
In one of my previous blogs, I explained how to force workflow on Components. Here I am going to explain how you can force workflow on Templates (TBBs, CTs and PTs).
Forcing Workflow on Templates:
Before forcing workflow on the items, you should always enable the workflow on that particular publication otherwise new and updated items would be waiting forever for a workflow to be enforced, as user would not be able to trigger a workflow process on the templates.
To do so, open publication properties and inside workflow tab check the checkbox "Enable Workflow Process Associations in Shared Schemas and Structure Groups" and save the publication properties.
2. Force the workflow on design items:
To force workflow, open publication properties and inside workflow tab check the checkbox "Any changes made to a Template in this Publication require approval by a Bundle Workflow Process" and save the publication properties.
Once the workflow enforcement on templates is set on the publication, Now if you updates/creates template (or TBB) outside of workflow, Instead of being checked-in and available for use, a minor version of the template will be created in "Waiting for Workflow" state. To use this version, you must add it to a bundle and start the workflow on it. Once the workflow is finished, the minor version is converted to a major version and is ready for use.