http://qs321.pair.com?node_id=656903


in reply to Re: functions with optional arguments in Windows DLLs
in thread functions with optional arguments in Windows DLLs

Indeed, you're right about optional arguments in C. So I guess the DLL I'm looking at (rmchart) wasn't written in C, but probably some kind of Basic). This is how the particular function I'm interested in is described:
nResult (LONG) = RMC_Draw2File( ByVal nCtrlId (LONG), ByRef sFileName (ASCIIZ), Optional ByVal nWidth (LONG), Optional ByVal nHeight (LONG), Optional ByVal nJPGQualityLevel (LONG) )
And judging by the description, the behavior I need happens when the optional args are not provided.