Assignments are, in [B/D], simple linear combinations of quantities. We can look at the assignments that we have just retained by entering the following:
BD>look:(a) 
Figure 20: Assignment definitions
giving the output shown in figure 20. What we are shown are all the assignments defined so far: these two directions. (Compare them with the canonical directions output in figure 14: they should be the same.) In future, we can continue to use the LOOK: (a) command to check on our assignments. The main use we make of assignments is in constructing further quantities, and we will illustrate how we do this by using the BUILD: command.