<p>They typically indicate their place in a sequence. For Example, M408K is the first in a sequence for calculus (an alternative to M408C). But I’ve also seen it mean absolutely nothing, at least in terms of a sequence. According to the Registrar page (<a href=“http://registrar.utexas.edu/schedules/102/using/index.htm[/url]”>http://registrar.utexas.edu/schedules/102/using/index.htm</a>) courses within a department are alphabetized by field, so it is likely the final letter is something assigned by the specific department according to a key they have established for their course offerings.</p>