I was in the weekly status meeting for one of our projects when I uncovered an integration requirement that wasn’t defined anywhere in our requirements documentation. When I asked the product owner why this was the case, he said that it was an implicit requirement, and that all software we develop should have it.
I’m sure we’ve all been here at one point or another but when it comes down to it, it’s not the PO’s fault. It’s our job when gathering requirements to bring these types of assumptions to the surface. Requirements documentation doesn’t care whether a requirement is assumed or hand delivered from the president, it just needs to be there. Getting the stakeholders involved (really involved) in the requirements process is another blog post altogether. Anyway, implicit or not, make sure it’s out there for everyone to see.