An file is the compiled version of an MQ4 source file. Since the 2014 update to MetaTrader 4 (Build 600+), MetaQuotes significantly upgraded their encryption and compression.
: Projects like ex4_to_mq4_cli are not decompilers themselves; they require a separate, often outdated executable ( ex4_to_mq4.exe ) to function. ex4 to mq4 decompiler github verified
The Repo That Learned to Speak MQL4