A secondary cross-sectional function, which requests that the primary function be calculated separately for the stocks from each separate IncludeList
Counts the number of stocks in the same IncludeList as the current stock.
The ListNum of a symbol is the number of the first IncludeList that it appears in.
The above example is therefore only useful when each IncludeList contains unique symbols.
The secondary cross-sectional ranking functions all work this way. For example a stock cannot belong to more than one sector or industry.