Why does DATETIME18. format use 2 digit years?

[Tom]

Anyone know why the DATETIME18. format uses only two digits for the year?

Unless my math skills have slipped 9 + 1 + 8 = 18 should be enough for DATE9. plus TIME8. with space for a colon between them.

Looks like it has done this for a long time as here is an article from 1999 about a problem it caused. 

557 - SAS/GIS sample map data sets use DATETIME18. format for DATE variable

[PGStats · Accepted solution]

PERCENTN. has the same kind of quirk, it requires two extra spaces for parentheses that it is designed not to write. I guess that is the plight of long term compatibility, once a less than ideal feature is installed, you are more or less stuck with it.

PG