Caps are codes that act as adaptors, enabling models to use NUOPC standard component interfaces. They are called caps because they "sit on top" of user code and call into it. They contain translations of native model data structures into ESMF data structures.

For documentation of caps, see the Earth System Prediction Suite (ESPS) site. Find the components on the table on the landing page, and follow the corresponding Code Access and Documentation link. Not all listed components have documented caps. The ESPS is a collection of components that are compliant with NUOPC conventions.