I follow a dev=trunk release=branch convention. this works great for the source code but what do ppl do for the documentation (unfortunately it is in MS Word (LaTex is too much for our corporate business/system analysts).
do you also keep docs on a branch and merge (it is a pain) after release?
or do you keep docs only on trunk?
You should have the document with the relevant branch. Otherwise, you could get in a pickle with documentation that doesn't match the features, etc of a particular branch. Especially if you need to have a separate branch for a customised version of your product that doesn't get merged back to trunk.
Rule #1 of documentation is it must be kept in sync with the code. Obeying this rule requires that the documentation be branched and merged along with the code. When merges are required, you can use the compare feature in Word or some other solution to tell what changed.