EDIT: I spent more time reading into this, the individual manufacturer of the vehicle has a lot of control over this. The OBD2 DTC has some standard items but is not required to have a time stamp or indication of age, which is more-so what I think you are looking for in the raw data.
I think the only way you can answer this question is having access to the engineering materials/information from the manufacturer. Maybe with some searching you can find an engineer who has worked on the OBD2 section and can tell you for the manufacturer they worked for. Although since it was standardized (in the US) in 1996, I would bet most of the systems haven't changed much.
I do know from my personal experience in "convincing" my car to pass state inspection that a stored code can become a non-stored code. This leads me to believe as I said below that the data is logically separated in the ECU's memory.
Your classification of codes is highly dependent on what scan tool you use.
I am not sure what you mean by "active/current, history/past, potential/memory" but there are two classifications for DTCs when stored in an OBD2 system, potential/pending, and logged/stored. I don't believe this information is stored in the DTC as they are logically separated in the OBD2 compliant car.
The car's ECU classifies DTCs at runtime after checking for a set of conditions. A less severe issue get's classified as pending until the condition occurs X more times. Upon occurring X more times, the code will be reclassified from pending to stored.
A common example of a pending is my Infiniti I30 always has a pending code for the crankshaft sensor. The condition for some reason occurs on startup but never repeats so the DTC never moves to logged/stored and the CEL never comes on.
In short, the classification of pending -> stored seems to be up to the car manufacturer.
A good answer covering some of the things you need to consider about OBD2 is in a fellow stackexchange answer here: Do fault codes get recorded with a time stamp into a log with a history of DTCs?