Participating apprentices should be older than 16 years; they normally spend four days each week in an enterprise to acquire work experience, and one day in an MITD training centre for theoretical and technological back-up. Apprentices undergo block release (two weeks’ duration), centre-based training at the start of the apprenticeship to enable them to develop the basic initial skills required for engaging effectively in the on-the-job training. Hie conditions of apprenticeship training are governed by a contract which is signed by the employer and the apprentice (or their responsible party).