Parameter substitution
A mechanism that enables feeding back information by replacing placeholders in generic message strings with real-time data.
Example
In the language file…
In the application…
Order {0} cannot start after end date ({1}).
Order 6501.01 cannot start after end date (06-10-2011).
Cannot change the order’s status from {0} to {1}.
Cannot change the order’s status from Archived to Active.
* 
Parameters occur in error, warning, and confirmation messages.