There are even more options to choose from. The mentione lev-\appserver\- file-structrure on the OS level has a rather complex structure with nesting for autoexec / config / os-scripting.
Doing the necessary modifications at this level is dictating that each appserver contect has a special meaning. Of course you can combine this with some user overwrites giving more freedom.
For formats macro-s and more you will need this OS configuration file approach.Within the autoexec/scritping approach you could implement logic for shifting dates, or more kind of those. That is not possible with metadata only definitions. The approach is similar as the old dates but done centrally.
Other people mostly with an OLTP DBA background are wanting the definition including the physical naming as only metadata defined. The behavior is a little-bit different when you are limited to a webbased predefined code (no analytics) as one were analytics is the major goal. When you can force only predefined code usage and only metadata bound access you could try to control (in fact overrule) OS security. As a chain is as strong as the weakest shackle ....
Some links of blogs:
Choosing the correct autoexec file for the job
http://blogs.sas.com/content/sgf/2013/05/15/pre-assign-sas-libraries-if-so-which-method/
Using Autoexecs with SAS Enterprise Guide
---->-- ja karman --<-----