ahdavidson - this is exactly what I am saying.
Udo Klein - I know to do this, yes; but short of downloading the library, unzipping it, etc - to get to that .h file on a computer on which I don't have the Arduino IDE installed doesn't make much sense in order to find out what type a particular argument is.
In the case I mentioned, I was at work, on a computer which didn't have the IDE or the tone library installed, so I went to the doc page, and...no argument types.
Yes, there are other ways, but they may not be available for all libraries, or they would involve more steps than it is worth to answer a simple question; the type definitions should be in the docs...
