MQL5 ReferenceConstants, Enumerations and StructuresCodes of Errors and Warnings Trade Server Return CodesCompiler WarningsCompilation ErrorsRuntime Errors Codes of Errors and Warnings This section contains the following descriptions: Return codes of the trade server – analyzing results of the trade request sent by function OrderSend(); Compiler warnings – codes of warning messages that appear at compilation (not errors); Compilation errors – codes of error messages at an unsuccessful attempt to compile; Runtime errors – error codes in the execution of mql5-programs, which can be obtained using the GetLastError() function. Economic Сalendar structures Trade Server Return Codes