Header arguments in Org mode properties

Header arguments in Org mode properties

Buffer-wide header arguments may be specified as properties through the use of #+PROPERTY: lines placed anywhere in an Org mode file (see Property syntax).

For example the following would set session to *R* (only for R code blocks), and results to silent for every code block in the buffer, ensuring that all execution took place in the same session, and no results would be inserted into the buffer.

#+PROPERTY: header-args:R  :session *R*
#+PROPERTY: header-args    :results silent

Header arguments read from Org mode properties can also be set on a per-subtree basis using property drawers (see Property syntax). When properties are used to set default header arguments, they are always looked up with inheritance, regardless of the value of org-use-property-inheritance. Properties are evaluated as seen by the outermost call or source block.¹⁷¹

In the following example the value of the :cache header argument will default to yes in all code blocks in the subtree rooted at the following heading:

* outline header
  :PROPERTIES:
  :header-args:    :cache yes
  :END:

Properties defined in this way override the properties set in org-babel-default-header-args and are applied for all activated languages. It is convenient to use the org-set-property function bound to C-c C-x p to set properties in Org mode documents.