Starting with 4D 6.7.2, entering a short date such as 08/06/29 means that you've entered June 8, 2029. Entering 08/06/30 means that you've entered June 8, 1930. This is because the pivot year in 4D is 30, which means that:

• All 2-digit years lower than 30 will be interpreted as 20xx.
  
• All 2-digit years greater or equal to 30 will be interpreted as 19xx.
  

You can change the pivot year using the SET DEFAULT CENTURY command.