System-wide header arguments

System-wide values of header arguments can be specified by customizing the org-babel-default-header-args variable:

     :session    => "none"
     :results    => "replace"
     :exports    => "code"
     :cache      => "no"
     :noweb      => "no"

For example, the following example could be used to set the default value of :noweb header arguments to yes. This would have the effect of expanding :noweb references by default when evaluating source code blocks.

     (setq org-babel-default-header-args
     (cons '(:noweb . "yes")
     (assq-delete-all :noweb org-babel-default-header-args)))