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I renamed the internal function to SoundAlert. Not optimal but the only thing that could be done.

Damnit. I never considered this name clash.

Could it be that it's expecting the [url=https://github.com/rheit/zdoom/blob/master/wadsrc/static/zscript/actor.txt#L303]function[/url] version of NoiseAlert instead of the [wiki=NoiseAlert]action special[/wiki]?

Try adding a space between 0 and {.

actor zomn:zombieman replaces zombieman{
	states{
	pain:
//		POSS G 0 NoiseAlert(0,0)
		POSS G 0{NoiseAlert(0,0);}
		goto super::pain
	}
}

Script error, "decorate.noisealert.txt:DECORATE" line 5:
Expected ',', got '0'.

Test file:[code]actor zomn:zombieman replaces zombieman{
states{
pain:
// POSS G 0 NoiseAlert(0,0)
POSS G 0{NoiseAlert(0,0);}
goto super::pain
}
}[/code]

As above, trying to run it gets this:[code]Script error, "decorate.noisealert.txt:DECORATE" line 5:
Expected ',', got '0'.[/code]but if I comment out the other line instead it works as expected (if you use a non-alerting weapon to put the zombieman in pain then then other monsters will be awakened targeting the zombieman instead of you)