After Reading What kind of barcodes are supported by the Point of Sale ?, its quite obvious that openERP may use Prefixes within EAN13 barcodes for special actions.

The question is, what is the best strategy to use EAN13 digits efficiently? in order keep things in order and not to rebarcode all/some items over and over again, as we face some cases like sale in seasons, items with dual price..etc

If some one can give an example or lead to existing one, I will be grateful..%