7.2. Subset Inclusion Lattice¶
VisIt relates all possible subsets in a database using what is called a Subset Inclusion Lattice (SIL). Ultimately the subsets in a database are cells that can be grouped into different categories such as material region, domain, patch, refinement level, etc. Each category has some number of possible values when taken together form a collection. A collection lets you group the subsets that have different values but are still part of the same category. For example, the mesh shown in Figure 7.1 is broken down into domain and material categories and there are 3 domain subsets in the domain category. VisIt uses the SIL to remove pieces of a database from a plotted visualization by turning off bottom level subsets that are arrived at through turning off members in various collections or turning off entire collections. When various subsets have been turned off in a SIL, the collective on/off state for each subset is known as a SIL restriction.