Deleting an Input Parameter in a Relation

	This task shows you how, when used in a relation, a deleted parameter is automatically replaced by a clone one with the same value.
	When a parameter in a set of relations is deleted, a clone parameter replacing this particular parameter with the same value is automatically created. It prevents the relation from being destabilized. For example, if a parameter called Length.1 is being deleted, a clone parameter replacing it and called deleted_Length.1 is automatically created. Note: If the relation is evaluated after a deletion, it will behave exactly as if the input parameter had not been deleted.
	Example: if (Length.2 <> 4mm) {if (Length.1 == 2mm) Message ("A") Else Message ("B") }
	In this example, if Length.1 is deleted knowing that its value was 2mm, the value of this parameter is maintained and if the rule is then evaluated (by the modification of Length.2 to another value different than 4mm for example), the message ("B") will be prompted.