Computation in Superposition (Comp-in-Sup) is a sub-field of Mechanistic Interpretability (Mech-Interp).
Superposition in this context means storing information in an overcompleet basis. Comp-in-Sup is the study of how (and if) neural networks performs computation, using information stored in overcomplete basis. The reason we want to do this, is because this information could inform better feature extraction methods.