I'll try to be as efficient as possible.
The concern I have regarding casual workers is that you get somebody for a short period of time to meet an immediate need, but there is no merit test and no language requirement. There are no requirements that are statutory or regulatory, as you have for other kinds of hires. There is no national area of selection requirement. It is really very much up to the manager as to what kinds of requirements may be imposed. There are none of the standard tests we have about entry into the public service.
When somebody has one of these jobs, it gives them an opportunity to learn about the public service and to have connections, and it then gives them an advantage over other Canadians in entering into permanent jobs. Casuals can be at any level; they tend to be administrative support, but not always.