Hi Claire,
There’s a couple of ways you can create the link.
If you have created a link that mentions the revision in the URL then you will always link to that revision. This means when it becomes obsolete or inactive the link will still take you to that revision.
If you created a link to the document only then this will take you to the active revision every time.
You can find the details at Using the Document Retrieval Service (DRS)
If you want to double check what you’ve used previously you can inspect the URL for the below.
Linking to the document (i.e. always active) will look like below (notice the word active in the URL):
<servername>/QPulseDocumentService/Documents.svc/documents/active/attachment?number=DOC1
Linking to a document revision will look like below (notice the revision number in the URL):
<servername>/QPulseDocumentService/Documents.svc/documents/revision/attachment?number=DOC1&revision=1&attID=2