  A MILP model for an extended version of the Flexible Job Shop Scheduling
problem is proposed. The extension allows the precedences between operations of
a job to be given by an arbitrary directed acyclic graph rather than a linear
order. The goal is the minimization of the makespan. Theoretical and practical
advantages of the proposed model are discussed. Numerical experiments show the
performance of a commercial exact solver when applied to the proposed model.
The new model is also compared with a simple extension of the model described
by \"Ozg\"uven, \"Ozbakir, and Yavuz (Mathematical models for job-shop
scheduling problems with routing and process plan flexibility, Applied
Mathematical Modelling, 34:1539--1548, 2010), using instances from the
literature and instances inspired by real data from the printing industry.
