It's is done to simplify localization. You can open app.h and change all message to anoher language in one place.

>I'm just exploring some of VFP's foundation classes. I ran across this:
>
>

>In app.h is this:
>#DEFINE ERROR_IN_ERROR_METHOD_LOC    "Error in error handler"
>

>As far as I can find it's only used in one place in _error class.
>
>What's the point of defining something in an include file that only gets used once?
>
>
>Assuming that they put it there so that it's available to me, how would I ever enen know that it's there? If I'm subclassing a foundation class, I'm not going to study every line of code in it to see what's available.
>
>TIA