> ## Documentation Index
> Fetch the complete documentation index at: https://docs.occtoo.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Track usage of source data
> See which providers write to a source, which cards read from it, and which properties are used where.
## On the source
The source page header carries up to three chip rows showing everything connected to the source.
* **Providers** — the data providers allowed to write to this source. Each chip opens the **Data providers** tab, scrolled to that provider and highlighted.
* **Cards** — the cards built on this source. Each chip opens the card.
* **Shared ID** — the sources this one shares entry IDs with. Each chip opens that source.
A row is hidden when it is empty, so a source with no cards built on it shows no **Cards** row at all.
The source list gives the same information at a glance, as an **In use** or **Not in use** badge on each card — see [Find sources](/guides/studio/sources/find-sources).
## Per property
The **Used by** column in the **Properties** widget names the cards that use each property, as links. Beyond four, the remainder collapses into **+n more** with the full list on hover. A property no card uses shows `—`.
Clicking a card name opens that card scrolled to the property, so you can see how it was mapped.
Cards that have been deleted are filtered out of **Used by**, and they do not block deleting the property either — see [Delete a property](/guides/studio/sources/delete-a-property).
## Why it matters
Usage is what blocks destructive actions:
* A source cannot be deleted while any card is built on it or any provider references it.
* A property cannot be deleted while a card uses it.
* A conversion target cannot be removed while a card exposes the property as that type.
Checking these chips and the **Used by** column first tells you what you would have to unpick.