Copying from the documentation:
Report column templates provide you with control over the results of a row from a SQL query. This type of template defines a cell, not an entire row.
Each report template identifies column names using the syntax
#1#, #2#, #3#, and so on. You can also name columns using column name substitution syntax such as
#EMPNO#. You can reference any item from your application within your template. For example, to reference an item called
ABC.in your template, you could include the exact substitution string
&ABC.. The actual value of ABC. would be provided by an end user editing an item in your application named
You can read more here: 13.2 Customizing Templates.