BCP for use of o, ou and cn attribute types

[Jason Lixfeld <jason+lists.openldap@lixfeld.ca>]

Is there a best common practice for when and where to use these 
attributes?  RFC2256 describes the 'o' attribute as "This attribute 
contains the name of an organization".  Is "organization" in their 
description supposed to be taken ambiguously, such that organization 
can be a system specific organization called "uid", or does 
"organization" actually mean XYZ Company Inc. by their definition?

Similar questions for organizationalUnit and commonName.  Both 
descriptions seem somewhat ambiguously defined.  Is this the case and 
one is free to use each one as you see fit based on whatever criteria 
the like, or is each attribute tailored to a specific task as a best 
practice?