The number of the first import IncludeList which contained this symbol
See also InList, which can be used to check whether the current symbol was in a specific IncludeList.
For an import where each symbol only appears in one include list, ListNum==n is equivalent to InList(n).
InList(n) will always be true when ListNum==n, but ListNum==n will only be true if n is the first list to contain the symbol.
When CIIFamily and CIILevel are used with Norgate Import, corresponding industry index symbols are automatically imported for each specific symbol that has one. These automatically imported symbols are placed in a virtual include list with the number 99.
See industry_indices.rts in the Examples folder for further clarification on how this CII mechanism works.