Build 4.0.0.56 of xlsgen adds read/write and calculation support for the hidden function DATEDIF(). Support is added for integrity purposes.

The official Microsoft documentation is here.

Syntax : DATEDIF(start_date ; end_date ; mode)

Calculates the number of days, months, or years between two dates. This function is provided for compatibility with Lotus 1-2-3.

modes :

• "y" : calculates the number of complete years
  
• "m" : calculates the number of complete months
  
• "d" : calculates the number of days
  
• "md" : calculates the number of days, ignoring months and years
  
• "ym" : calculates the number of months
  
• "yd" : calculates the number of days, ignoring months years