The Uniform Practice Code is the FINRA bylaw that sets guidelines for how industry members transact business with other members. The Uniform Practice Code establishes such things as settlement dates, rules of good delivery, and ex dividend dates.
Applying "Uniform Practice Code" to Securities Exams:
The Uniform Practice Code sets a standard of practice for how broker dealers conduct business with each other. The securities industry could not operate effectively if the members of the financial services community did not have a reasonable understanding of how trades were going to settle, the rules constituting good delivery, how and when securities trade ex dividend etc.. The UPC sets standards for most broker dealer interactions with each other.