<Formula>
There can be zero or more <Formula> elements as children of the <CSL> element. The value of each element must be the name of an output for which a row should be generated.
Note: It is impractical to list all the possible formula values. To extract a list of all valid formula values for the current node, run a report that specifies the getAllFormulas attribute to the <CSL> tag. See "Figuring Out What Variables to Use" on page 1.