org-add-link-type is a compiled Lisp function in `org.el'.

(org-add-link-type TYPE &optional FOLLOW EXPORT)

Add TYPE to the list of `org-link-types'.
Re-compute all regular expressions depending on `org-link-types'

FOLLOW and EXPORT are two functions.

FOLLOW should take the link path as the single argument and do whatever
is necessary to follow the link, for example find a file or display
a mail message.

EXPORT should format the link path for export to one of the export formats.
It should be a function accepting three arguments:

path the path of the link, the text after the prefix (like "http:")
desc the description of the link, if any, or a description added by
org-export-normalize-links if there is none
format the export format, a symbol like `html' or `latex' or `ascii'..

The function may use the FORMAT information to return different values
depending on the format. The return value will be put literally into
the exported file. If the return value is nil, this means Org should
do what it normally does with links which do not have EXPORT defined.

Org-mode has a built-in default for exporting links. If you are happy with
this default, there is no need to define an export function for the link
type. For a simple example of an export function, see `org-bbdb.el'.