Run the code below, using the same numeric_mask on a form, putting different numbers into the form. The mask will sometimes round / truncating

DAW, please confirm whether this is a bug, or am I missing something from the documentation. Thanks.

Code:
Use DfAllEnt
Object oMain is a Panel
 Object oForm is a Form
  Set Size to 12 50
  Set Numeric_Mask Item 0 to 10 4
 End_Object
 Object oButton is a Button
  Set Location to 12 0
  Procedure OnClick
   Set Value of oForm Item 0 to 79.84495
   Send Info_Box "Truncating"
   Set Value of oForm Item 0 to 179.84495
   Send Info_Box "Rounding"
  End_Procedure
 End_Object
End_Object
Start_UI