The date processing is one of the worst-documented features, and there are conflicts in the documentation between MS-XLS (XLS files), ECMA-376 (the office open

The date processing is one of the worst-documented features, and there are conflicts in the documentation between MS-XLS (XLS files), ECMA-376 (the office open xml standard), and MS-XLSX (describing how excel deviated from ECMA-376 -- yes, this exists and is pretty substantial). To give an example, in some versions of excel `e` refers to the "era", which is the year for US versions. However, the documentation and individual implementations disagree as to what they actually mean: Some versions treat "e" as the 4-digit year and "ee" as the 2 digit year. Other versions treat "e" and "ee" as the 4-digit year. Others treat "e" and "ee" as the 2-digit year But the worst offender is format code 14, which actually depends on the client calendar type, so you get different results in different versions of excel