An expression chart is constructed using one or more contracts, numerical constants, and simple mathematical operators (+ - * /). Using the "Default" Aspect" for the given contracts, the chart will perform the calculations and plot the results on the chart using the "line" plot style.
Contracts used in an expression can be the explicit contract (WK01, SPU1, etc.), a nearby contract (W1!, SP1!, etc.) , or a forward contract (W3!, SP4!, etc.). The continuation chart symbol "%", along with all of its associated parameters, is also supported in an expression.
Expressions are entered directly in the Symbol field, and are calculated from left to right. Use parentheses to change the order of the calculations, and make sure you use a space between each contract, numerical constant, and mathematical operator:
Examples:
DJY - SPY
(NG1! + NG2! + NG3!) / 3
W1! - (C1! + O1!)
W1! - %C1!;7EH;B
Notes: Chartable expressions do not display the Open, High, Low, Close and Change fields in the chart's header or Data View window: they simply display the result of the expression.
Certain studies will also not be available for plotting on an expression. If the study uses a contract's Open, High, Low, Close or Change fields (or some other data which is not available as a result of the expression's calculation), that study is simply hidden on the Study drop-down list as long as the expression is displayed on the chart.