Yes, you can use any kind of variable inside a type, even variables of other types as well.
A different thing is initializing those variables, since there is no default constructor/destructor for types because they are not objects; what I do to overcome that issue is defining an "init" function for my types which I call immediately after defining them, such as:
LOCAL abc as MyType; abc.init()
In "init" is where I DIM arrays, for example.