org-coderef-label-format

org-coderef-label-format is a variable defined in `org-src.el'.
Its value is

"(ref:%s)"

Documentation:
The default coderef format.
This format string will be used to search for coderef labels in literal
examples (EXAMPLE and SRC blocks). The format can be overwritten in
an individual literal example with the -l option, like

#+BEGIN_SRC pascal +n -r -l "((%s))"
...
#+END_SRC

If you want to use this for HTML export, make sure that the format does
not introduce special font-locking, and avoid the HTML special
characters `<', `>', and `&'. The reason for this restriction is that
the labels are searched for only after htmlize has done its job.

You can customize this variable.