I was pointed towards the following page as part of a discussion on another forum which was instigated by a thread on this forum:
Pentax Tags
These folks, (physics students at Queens University in Toronto, judging by the URL) are decoding the various data fields in the EXIF data.
What I found interesting was the Pentax LensType Values section, about 1/3 of the way down.
Prefacing it they say:
"Note that newer series numbers may not always be properly identified by cameras running older firmware versions."
Does this mean that the camera stores lens type information in an internal data base, which, if not updated through firmware makes the camera unable to properly recognize lenses that were marketed after the camera was built?
It appears that there are two ways (in Pentax's world) of identifying the lens used. One is in the camera's firmware, the other in external software (PhotoME, etc).