Service Level Agreements
Some website providers have different service level agreements such as sizeable corporate website providers Like Telstra or Sensis and software as a service providers such as Weebly or Adobe Catalyst.
So if this is the case, make sure you get a copy of what is included and what is not.
Often to add an extra page or function to the site can add to the additional expense of jumping up to the next service level plan.
So check the agreement carefully.