To preflight PDF documents, you use Preflight Profiles. A Preflight Profile is a collection of criteria, which a PDF document should meet to be outputworthy. For each criterion, you can specify:
Moreover, some criteria allow you to specify how detected problems, if any, should be fixed.
An example of a criterion is RGB colors. If you do not want RGB colors in your PDF documents, you can check this and have all RGB colors converted to CMYK.
As of PitStop 13, you can even limit your checks to a particular selection. You can for example apply one check to all odd pages, and another check to all even pages.