There is a term "catalog year," which refers to the year in which a university catalog (graduate or undergraduate) takes effect, together with the requirements (such as degree requirements) and regulations prescribed therein. With some exceptions, students are entitled to graduate under the catalog that was in effect during the first semester of their matriculation.

Read the information provided at http://www.uh.edu/academics/catalog/general/acade3.html#degrees_granted. Scroll down to Graduation Under a Particular Catalog.