It allows the system administer to define a field on extended table differently from those field on parent table without affecting the parent table or its extended tables.
e.g. A field on a Parent P1 table, a dictionary override can change the default value on Child C1 table without affecting the value on Parent P1.
How do we do dictionary override
Open Parent from or search for system definition on left navigation
Left navigate Sys Definition -> select dictionary -> new dictionary entries -> Select table -> Type (field) -> column label -> column name -> Check fields Mandatory & Display -> Submit.
Now open Child table -> click on field which want to override -> Right click -> Select Dictionary -> Click on tab Dictionary override -> click on New -> Select Override Mandatory.
We can also override field like Override Reference Qualifiers, Override Dependant, Override Attributes, Override Default Value, Override Read Only, Override Calculations, and Override Display Value.
Note: You can add dictionary overrides only on tables that are in same scope.