Deriving user interface requirements is a key step in user interface generation and maintenance. For single purpose numeric routines user interface requirements are relatively simple to derive. However, general numeric packages, which are solvers for entire classes of problems, are densely interleaved with strands shared and mixed among user options. This complexity forms a significant barrier to the derivation of user interface requirements and therefore to user interface generation and maintenance. Our methodology uses a graph representation to find potential user decision points implied by the control structure of the code. This graph is then iteratively refined to form a Decision Point Diagram, a state machine representation of all possible user traversals through a user interface for the underlying code.