Hello,
maybe I can clean up the things about the "Model Revision" a little bit.
First, about me: I'm the author of PhotoME.
Since Pentax does not provide any informations about the maker notes, the complete maker notes decoding base on reverse engineering - not only by me and the PhotoME users, but also by Phil Harvey (author of ExifTool) and the users of his software.
Many things can be figured out by taking some shots using the camera and compare them. For example the Hometown city tag (0x0023) was easy to decode by shooting different images with different settings and then compare the data the camera write to the metadata.
Other data can't be set or seen on the camera, like the "CameraInfo" tag, which contains 5 LONG (unsigned 32-bit) values:
"Pentax Model", "Manufacture Date?", "Model Revision?" and "Internal Serial Number?".
Here you can only guess their meaning.
By comparing shots of different cameras it's easy to see that the first value is the same for the same model and different for different models. That means this must be a model-identifier (the "Pentax Model").
The second value looks always like a date. Since it indicate a date before the user bought the camera, it must have something to do with the manufacturing of the camera. But that doesn't mean it's the date where the camera was assembled - it could be also the date were the EEPROM was last written, or something like that. That's why PhotoME show a question mark behind the tag title.
The only thing which is definitely, is that this date is important enough for Pentax, that they decided to write it into the metadata.
The third and the fourth values are combined by PhotoME to one value, because both numbers are always very low, so it looks like a version number and sometimes it increase after the camera was serviced. That these 2 numbers are a "Model revision" is just a guess (indicated by the question mark).
Maybe these 2 numbers don't need to be combined. Maybe they are no version number and have a totally different meaning.
Like some users in this thread figured out, the first number change to 8 after the camera was serviced. That's an very interesting observation. I wonder if it change again if the camera was a second time in the service.
Maybe the second number isn't a sub-version - it could be really everything, a ID of the factory which manufactured the camera, a ID of the assembly line in the factory, or an ID for the market for which it was built (Europe, America, Asia...).
It could really mean anything - and I'm very thankful for every hint or idea.
The same count for the last value, which is shown as "Internal Serial Number?" by PhotoME. It seems to be unique for a model and seems to increase for different cameras of the same model - just like a serial number. I've already heared from people that this serial number changed while the camera was serviced. That means Pentax either replaced the complete camera (which is unlikely), or at least the part where the this number come from.
Only Pentax can tell what these numbers really mean - but they don't seems to be very interested.
I wish they would enlighten these things a little bit, but I assume this will never come true.
Cu, Jens