MQL4 Reference Chart Operations ChartSetDouble
Sets a value for a corresponding property of the specified chart. Chart property should be of a double type. The command is added to chart message queue and executed only after all previous commands have been processed.
[in] Chart ID. 0 means the current chart.
[in] Chart property ID. Can be one of the ENUM_CHART_PROPERTY_DOUBLE values (except the read-only properties).
[in] Property value.
Returns true if the command has been added to chart queue, otherwise false. To get error details use the GetLastError() function.