I see the word 'baseline' used a lot in Quality Assurance. I don't know exactly what it means in this profession. I was reading a Test Plan, in it's Test Entrance Criteria section one item read as:
"Requirement documents are baselined and are under configuration/ version control"
I understand each update to the requirement docs should be subjected to version control in case we lose one version, we could retrieve a version before that but I don't understand what it means by the document being baselined.
Given that you have a baseline of something and can identify intermediate deltas, you should always be able to rebuild up to whatever defined point you want.
This is classic configuration management.
The baseline for a piece of code - as an example - is the complete component as it's initially stored to the CM archive. Deltas to that baseline are just that, not duplicate instances of the changed code, but just the changed code. If only 1 line of a code component changes, only that 1 line will be in the delta. Then, at some point, after you've made 27 little deltas to your original baseline, you can tag a new baseline, which again will be the complete component stored in the archive, including all the previous deltas.
With respect to QA deliverables, the baseline is - again - a known starting point against which changes can be documented. It might be a baseline requirement, against which project change requests can be attached. It might be a baseline configuration, against which documented configuration changes are made. It might be baseline data, which is perhaps what you refresh the environment to at the start of a test cycle.
For the specific instance you mention in your post, the requirement is baselined and archived in a CM system - probably marked v1.0 or similar.