If you have the EX4 and want to replicate its behavior, hire a programmer to "black-box" the logic. They can watch how the EA trades and rewrite the code from scratch. This ensures you have a clean, modern MQ4 file.

– While some repositories claim to offer decompilers:

Decompiling a commercial Expert Advisor (EA) is generally a violation of the End User License Agreement (EULA).

This is the raw, human-readable source code. Developers write and edit strategies in this format using the MetaEditor.