What does "-0" after the model signify?

I've been following multiple Tag Heuer watch listings on Chrono24 and ebay. Most of these watches have normal model designations on the back (some combination of letters and numbers, with no spaces). However, I have seen a few that have "-0" after the model designation. What does the "-0" signify? Is it an update to the model or movement? Or something else?

As an example, here's a picture that was posted on this site that shows the "-0":

Hi Bill
A common question. It means something has changed in the watch, though it may look identical externally. As to what, that's anyone's guess. Recently models have had the Heuer 02 movement replaced by the TH20-00 and so these models now have a 0 added to the number.