When generator definitions expand beyond what is comfortable to write in a single generator, you can split your generator into sub-generators. A sub-generator is just a normal generator definition, run with the subreport; 'generator name'; run; command from within another generator. The sub-generator is executed as if the full contents of the definition of the sub-generator were directly included in the definition of the parent generator. They thus inherit the same set of open files, and same generator stack as the parent. See the definition of the subreport command in the Section 5.3.4 for more details and ways of using sub-generators.

Generators whose names begin with '_' are hidden from the list shown to the user when choosing Generate... elsewhere than the Generator Editor (e.g. from a Diagram Editor). Names like this should thus be used for generators that are intended only for use as sub-generators, e.g. if they assume that the generation output is already going to a file, or that something other than a graph is already in the generator stack. If necessary, a user can still see and even run these generators elsewhere by holding down shift while choosing Generate....

Writing generators allows you to take advantage of some powerful object-oriented principles. If your generator follows subgraph links to a different graph type, it is often best to create a sub-generator in that graph type, rather than defining it in the original graph type. This is similar to choosing which class to define a method in when programming. Similarly, if a generator you write is applicable to more than one graph type, there is no need to duplicate it to both graph types: simply define it in a common supertype, or in the supertype of all graph types, Graph itself. This is similar to the principle of inheritance.