We recently made some changes to the functions handeling dates in ABC Analyzer.
These changes were made to mirror the way that Excel handles dates in formulas. As of version 4.1.0 of ABC Analyzer, the base date for all date operations will be Jan. 1st 1900.
There is one important difference from Excel though! Excel considers 1900 a leap year which by normal western calendar is not correct! This means that if your formulas in ABC Analyzer handle dates after Feb. 28th 1900 (which they probably do) the results will be off by one – compared to a similar formula in Excel.