Software development is driven by software comprehension. Controlling a software development process is dependent on controlling software comprehension. Measures of factors that influence software comprehension are required in order to achieve control.

The use of high-level languages results in many different kinds of lines of code that require different levels of comprehension effort. As the reader learns the set of arrangements of operators, attributes and labels particular to an application, comprehension is eased as familiar arrangements are repeated.

Elements of cognition that describe the mechanics of text comprehension serve as a guide to assessing comprehension demands in the understanding of programs written in high level languages. A new metric, Kinds of Lines of Code Identifier Density is introduced and a case study demonstrates its application and importance. Related work is discussed.