I would like to add these updated and more accurate descriptions for extensions associated with MetaQuotes Language and MetaTrader platform.
MQ4:
MQ5:Brief: MetaQuotes Language 4 source code
Full: Program written for MetaTrader 4, an online trading platform for Forex, Futures, and CFD markets; may be a Custom Indicator, Expert Advisor, Script, or Library file. Contains source code written in MQL4 (MetaQuotes Language 4), typically includes variables, classes, functions, and comments.
.MQ4 files can be opened, edited and compiled into .EX4 files using MetaEditor, a specialized editor for creating trading robots and technical indicators.
Category: Source code and script file
Associated software: MetaTrader 4
MQH:Brief: MetaQuotes Language 5 source code
Full: Program written for MetaTrader 5, an online trading platform for Forex, Stocks, Futures, and CFD markets; may be a Custom Indicator, Expert Advisor, Script, or Library file. Contains source code written in MQL5 (MetaQuotes Language 5), typically includes variables, classes, functions, and comments.
.MQ5 files can be opened, edited and compiled into .EX5 files using MetaEditor, a specialized editor for creating trading robots and technical indicators.
Category: Source code and script file
Associated software: MetaTrader 5
Let me know if any details are needed.Brief: MetaQuotes Language header file
Full: Header file for MetaTrader, an online trading platform for Forex, Stocks, Futures, and CFD markets. Contains code written in MQL5 or MQL4 language, typically includes variables, classes, functions, and comments.
.MQH files can be opened and edited in MetaEditor, a specialized editor for creating trading robots and technical indicators.
Category: Source code and script file
Associated software: MetaTrader 5
Resophonic, http://www.mql5.com