Question: how to comment out multiple lines in batch file?
Answer: REM must be followed by a space or tab character, then the comment. ... 
If ECHO is ON, the comment is displayed. ... 
You can also place a comment in a batch file by starting the comment line with two colons [::]. ... 
You can use REM to create a zero-byte file if you use a redirection symbol immediately after the REM command.