Global variable vs common block

[marc <m_schellens(at)hotmail.com>]

hello everybody,
	
I have a very large program which uses common blocks (sorry David),
nowadays I don't like them any more (never liked them but lately I
discovered the DEFSYSV command :-). I used for the whole program just
one common block holding one structure (all the global data).
It was easy to change the suff to use a ('!named') global variable, and
at a first look everything seem to work fine.
So my question is: Is there something I have not thought about/do not
know were I can run into a limitation with this?
Wanna know this before I spent more time on the prog and eventually have
to change it back.

thanks,
:-) marc