This is the official manual for the latest Org-mode release.
:sep header argument can be used to control the delimiter used
when writing tabular results out to files external to Org mode. This is used
either when opening tabular results of a code block by calling the
org-open-at-point function bound to C-c C-o on the code block,
or when writing code block results to an external file (see file)
By default, when
:sep is not specified output tables are tab