The SVN-controlled code generated data by controlling hardware and embedded the $Id$ of the controlling script in its output. I would then refer to the version ID later, when loading that data in for analysis. This accounted for any changes to the data-generating code.
For example, we tracked the orientation and direction of objects moving on a screen. One update redefined 0° to be up/north/12:00 instead of the +x direction used before. The code which loaded these files checked the $Id$ value and rotated the directional data so that the entire dataset used the same definition.
