org-store-link-props basically shoves everything into
org-store-link-plist (with some pre-processing). The plist keys are
what's used as keywords for %:
The :initlal is special; it gets mapped to %i, and :query is a list
not a string, so you can't use %:query although you can access it from
Emacs Lisp embedded in the template.
I don't have any secret knowledge, I just dug through the source code
and experimented with different inputs.
The code and/or documentation could be clearer
Kaushal Modi