Investment Studio > Setup > Chart > Source editor > Parameters

In the Parameters section, you can define constant float values for use in the selected source's Symbol definitions and output channels and (if combined with the source's identifier) throughout the Chart.

Parameters are a special kind of symbols. Like other symbols, they can be referenced in expressions, but they are not themselves defined using expressions. Instead, each parameter's value is specified explicitly in the parameter table.

There are two reasons to use Parameters instead of Symbols: they are slightly more efficient (since no expression evaluation is required to obtain their value) and parameter values can be modified on the fly from the Chart parameter window without having to open the source editor.

Each row in the parameter table

is a parameter record containing the following fields:

	The parameter Symbol can be used in references throughout the source. It should be unique within the source and follow the usual symbol naming conventions. Parameters can also be referenced outside the source where they are defined (output channels and symbol definitions in other sources; the Chart's captions). To do so, use a dot to combine the source's identifier with the symbol. For instance, the parameter _ndays in the source _bol would be referenced as _bol._ndays. Use the built-in identifier grid to access field values (for the selected record) in the view's Grid object, as in grid._nav. Be sure to avoid name clashes with the Chart's Symbols and built-in symbols.
	The Caption is an optional string to be displayed above the parameter's slider in the Chart parameter window. If no Caption is specified, the parameter's Symbol is used instead.
	The parameter's Value is a float constant.
	Low is the lowest value which can be assigned to the parameter in the Chart parameter window. The parameter is excluded from the Chart parameter window unless Low < High.
	High is the highest value which can be assigned to the parameter in the Chart parameter window. The parameter is excluded from the Chart parameter window unless Low < High.
	Steps is the number of evenly spaced values (starting at Low and ending at High) which can be selected using the parameter's slider and spin buttons in the Chart parameter window. The parameter is excluded from the Chart parameter window unless Steps > 1.
	Check Locked to exclude the parameter from the Chart parameter window.
	The Comment can be any text; it has no effect on source evaluation or the Chart parameter window.

Parameter table entries can be added, copied, moved and deleted using the table's pop-up menu or the equivalent buttons in the window's upper right corner:

	New. Click to add an empty row to the parameter table. If a row is selected in the table, the new row will be inserted below the selected row, otherwise it will be added at the bottom of the table.
	Copy. Click to add a copy of the selected row to the parameter table. The new row is inserted below the original.
	Delete. Click to delete the selected row.
	Move up. Click to move the selected row toward the top of the parameter table.
	Move down. Click to move the selected row toward the bottom of the parameter table.