Pao with 4 elements for date ranges

i will be memorizing date ranges for an upcoming project. i have a pao already and would like to add an element like adjective or accesories so i can get ranges like 0000-9999 down to one cycle.

do folks have suggestions for categories of fourth element?

am i going in the wrong direction?

thank you!

Assuming you have a PAO with 2 digits for each - could you potentially do PAOO?

I would be interested to know how people deal with that.

My solution for dates is to simply not encode the first digit. Because the difference means the dates are so far apart in time, I figure I won’t believe my sister was born in 987 or that king Sargon died in 1705. It would mean that I seriously mixed up historical periods!

And also 1705 BC, 705 BC, 705 and 1705 use the same reference (person) but they are at different places in my history memory palace, which gives me another cue.

For other big numbers (like in 12167 is the cube of 23) I use my shaper system (1 to 31, that I use normally for days in dates) as a prefix for the thousands… I feel like it’s a big cluttered to be honest (but then maths isn’t exactly a priority project for me so I didn’t bother looking for a better solution I just use what I already have at my disposal).