I agree. Also, some system assumed that 99 was a special code like not-available. [1] And I have a faint memory that some apps assumed that xx<20 means 20xx and

I agree. Also, some system assumed that 99 was a special code like not-available. [1] And I have a faint memory that some apps assumed that xx<20 means 20xx and xx>20 means 19xx. So the risk of a transition into caos was smoother and weirder. [1] The national ID numbers here in Argentina for foreiners started from 95, then 96, ... My university gave them fake internal ID numbers starting from 99 until they fill all the paperwork to get a real one. The national ID numbers used all the range do they decided to jump to 60, 61, ... (I'm not sure what happened with the 99 duplicates. I expect to see some weird collisions reports.) Anyway, the ID number for newborns reached 59 and then, the ID number for newborns jumped to 70.