This is not same as 'Salesforce API version'.
Objective: There is a VF page that renders as PDF which numerous users use. I would like to include in the footer my own running version number that is automatically generated (something like v1.0.1 or v2015.06.02.001 or anything). The version needs to update each time I modify the custom controller or deploy the code to a different environment or anything better if you may. It doesn't need to be sequential.
Purpose? To identify that two documents presented to me by different users belong to different 'versions' (source code) without looking through the actual content.
Is there an easy way to implement this?