Crystal Reports lets developers
create User Function Libraries (UFLs) that are recognized by the Formula
Editor. A UFL is a library of functions that is created by a developer to
address a specific need.
Crystal Reports lets you extend
the formula language with your own Java functions, and then package them in a
User Function Library.
When users create a report in the embedded
Crystal Reports Designer, they often create formula fields to
use in the report. These formula fields consist of variables and functions
provided by the
Crystal Reports Designer. Although a large collection of
functions are available, sometimes users need a customized function.