Parameter Passing

[jon@bdmrrr.bdm.com (Jon Humphreys)]

I'm currently trying to learn Ada by translating a program written
in BASIC (my employer's choice, not mine), and I've got a fairly
fundamental question: when passing parameters from one package
to another, is it possible to simulate something like a FORTRAN
common block by placing variables in a package and then 
using the package whenever I need to access/modify the variables? For
example, consider the following hierarchy:

				main
				 | 
			--------------------
			|  		   |
			A		   B
					---|---
					|     |
(B, C, and D are a package)		C     D

If a set of variables were used in procedures A and D, would it
be possible to create a package containing these variables and 
then include them in procedure A and D? Or should all the variables
be declared in main and then passed as parameters to A and B, and then
from B to D (this seems inefficient)? I guess what I'm asking is, which 
way would be considered correct in Ada? (Currently, we don't even have a 
compiler, so there isn't any way for me to test this kind of thing.)

Thanks for any help, 

jon