The rows and columns part of a table using the OASIS XML Exchange (CALS) table model. (This structure is available only in the Extended variants of NISO STS; it is not available in the Interchange versions of NISO STS.) In order to distinguish the OASIS XML Exchange (CALS) elements from the XHTML table model, all OASIS XML Exchange (CALS) table elements must be namespaced in NISO STS, by default using the OASIS URI and the namespace prefix oasis:.