Mq4 code has to be compiled into Ex4 format which is like a encrypted version of the code and this Ex4 file can only be executed on the MT4 platform, hence Ex4 files are used for distributing without exposing the code. Mq4 is the source code format for creating EA/Indicator/Script. MetaTrader platform comes along with Meta Editor, which is a code editor for MetaQuotes Language 4.
