As development of the GTVH progressed, a hierarchy of the KRs was established to partially restrict the options for lower level KRs depending on the KRs defined above them. For example, a lightbulb joke (SI) will always be in the form of a riddle (NS). Outside of these restrictions, the KRs can create a multitude of combinations, enabling a researcher to select jokes for analysis which contain only one or two defined KRs. It also allows for an evaluation of the similarity or dissimilarity of jokes depending on the similarity of their labels. "The GTVH presents itself as a mechanism … of generating describing an infinite number of jokes by combining the various values that each parameter can take. … Descriptively, to analyze a joke in the GTVH consists of listing the values of the 6 KRs (with the caveat that TA and LM may be empty)." This classification system provides a functional multi-dimensional label for any joke, and indeed any verbal humour.