Virtual table contents

[Eugene Kuznetsov]

Hello.

I've got a question regarding inner structure of virtual 
tables generated by different versions of g++. 
I did some testing with egcs 2.91.66. After a couple of
tests I found out that its virtual tables are arrays of
pointers, where actual pointers to functions begin from
 3rd position - first two seem to be reserved for other 
purposes such as RTTI or multiple inheritance. I played 
with compile options -fno-rtti and -fvtable-thunks, but
it didn't change anything.
 Here's the question. 
 Is there an universal way ( i.e. the way that would
be acceptable for all compilers since egcs 2.91 and 
higher ) to tell compiler NOT to use these two positions
and to start function pointers immediately from 1st 
position? Or such a way only for some specific versions
of compilers?

--
Thank you,
Eugene