As per this thread, we could add 24 other oscillator indicators to this mq4 file. I added a couple of comments in this source code, as you can see.
In below screenshot you can see the source code for RSI Power Maximum v2.03.mq4. RSI is an oscillator indicator.
In the EA parameter settings, we are able to select which 'oscillator' we prefer. There is a choice of 25 oscillators.