define("MSG", "Hi Sololearners", true); what does that true signify?

Answer 1

https://code.sololearn.com/wj4EW697Fx0G/?ref=app

Answer 2

case insensitive (true) or not (false)

Answer 3

it signify that if u declare a constant with a case insensitive you can write the output by just echo msg; without considering the uppercase of the constant name