So this means something like defining your own language? E.g.
But, really, you can just use a list for ordered pairs.
You can even pass an entire time series with JSON. http://vimeo.com/35005701
I sometimes wish JSON didn't allow any types of scalar data other than strings.
"Numbers are not quoted. It would be insane to require quotes around numbers." —Douglas Crockford http://www.json.org/fatfree.html