* '''System variable type operand''': Are system pre-defined variables. These values are replaced in run-time by pre-determined values, delimited by double quotes (") and preceded by star (#). By now only one variable is available: "#null" that indicates null values or fields.

=== Arithmetic Expressions ===

The arithmetic expressions relate two operands (value or another expression) to compose a sum, subtraction, multiplication or division.

* '''Sum (+)''': Sum two operands. Represented by the sum (+) character. The expression syntax is ''<operand/expression> + <operand/expression>''. '''Examples''': "Taxes" + "Commissions";

* '''Division(/)''': Divides two operands. Represented by the divide or bar (/) character. The expression syntax is ''<operand/expression> / <operand/expression>''. '''Examples''': "Total Value" / "Amount".

=== Relational Expressions ===

The relational expressions compare two operands (value or another expression) two evaluate if a condition is ''true'' or ''false''. Usually used with decision functions, like the ''IF''.

* '''Equal (==)''': Performs the equal comparison expression between two operands. Represented by the equal operator (==). The expression syntax is ''<expression> == <expression>''. '''Examples''': "Unit Price" == "Total Price";