The *%<function>%* tag is used to define both normal and aggregate functions. Name, type and returned data type have to be specified using attributes.

*name* - function name

*type* - either *normal* (default) or *aggregate*

*null* - *true* if function may return *NULL*, else *false* (default)

*returns* - return type: *string*, *int*, *real* or *datetime*

*length* - for *real* and *integer*

*decimals* - for *real*

Function parameters are defined using the *%<parameter>%* tag. Data private to a function is declared within the *%<data>%* tag. The *%<code>%* tag takes the code for normal functions, aggregate function code is put into the *%<clear>%*, *%<add>%* and *%<result>%* tags