Fab3000 is one of the only CAM software tools that can naively implement gerber data in a hierarchical fashion. This hierarchy allows you to simplify many cumbersome tasks and easily create complex panels that contain many different jobs all merged into a single set of gerbers.
Essentially Fab3000 consists of two hierarchical resources: Job, and Insert:
JOB - A single design (i.e. PCB) with its own unique layers, dcodes, and other attributes. (All data imported and 90% of editing are handled at the Job level). Note: In ODB++ terms, a Step is the same thing as a Job (in Fab3000)
INSERT - An insert represents the inclusion of one job as a part of another. The job containing the insert is the parent job, and the job that is inserted into the parent is the child job. Using this parent/child relationship, you can continue the hierarchy for as many levels as needed to express a complete design.
Note: For a more detailed explanation, please go to the FAB 3000 Help Guide, and check out the section: "Learn Guides | Merge Jobs".