It’s difficult, at best, to manage releases in terms of changed files. A change-based system will allow your Change Review Board to review and approve requests for a particular product stream and they will be able to clearly identify which of those changes are in each successive build. The promotion model will work on changes, build comparisons will be done in terms of changes, etc.
Establish Clear Consistent Release, Baseline, and Build Identification
Assign regular identifiers (build IDs) to the build increments and use them to track your testing and problem reports. Put the Build Ids in the customer executable (along with the tags used to define the variant subset) so that it is easy to go from a customer site back to the specific build information. This also makes it easy to track your customer sites in the delivery portion of your CM solution.
For release identifiers, I prefer short names, as you're going to want to combine them with other attributes and they'll take up valuable real estate on your reports and browsing tools. For example, R1, R2, R3 is sufficient. Release one may be more readable on its own, but it’s certain to shift other valuable info off the screen or page. Note that the release identifier is actually identifying the release stream. You will likely release more than one build from this stream to your customer base.
Make sure you have a CM tool that can help you with release identification. It should manage release identifiers, baseline identification, build identification (superset and variant), and it should do so in a regular, yet flexible manner.
Use your baseline numbering to identify major feature or quality differences. Tell the customer he has build R4 baseline 6 increment 12 [R4-6.12] and will be moving to R4-8.3. Give a major feature/fix summary of R4-7 and R4-8 to the customer ahead of time and let them know what they're getting. Then fine tune your process so that you move significant changes to the next significant baseline rather than upsetting the user by delivering a major change in the increment from R4-8.3 to R4-8.4.