[Samba] share level parameters in global space

[Chris]

Apparently many share level parameters for smb.conf can be specified at 
the global level which then applies to each share as the default unless 
overridden on a per share basis.

Is this true for all share level parameters? If not, is there a 
documented (or known) list of which ones work in this fashion and which 
ones don't (those that either must appear at the share level or are 
useless at providing a default for shares when placed in the global 
section)?

Thanks.

Chris