 The previous section focused on some of the ways one can take a system with a single modality and create a system with multiple modalities from it. Another alternative to build a multi-modal system is to take existing uni-modal systems, and then put them together by using a particular strategy. This section contains a brief description of some of the possible techniques; for a deeper discussion, the reader is referred to the SEP entry on  combining logics  by Carnielli and Coniglio (2016).