Type X is a messaging format that uses XML based standards. It’s a way of reducing some of the limitations within the Type B messaging format, particularly with respect to message size.
The take up of Type X has been mainly with airline partners or suppliers that have no need of legacy transmissions but can interchange messages with Type B users.
It’s is relatively new (in comparison with Type B history). It’s uncertain if there is a large take up of Type X at this stage.