I don't know of a public convention but have used the following in my own code :
var dfrd: a Deferred object (I've don't recall ever needing two or more in the same scope)var p: a Promisevar p_foo: one of several named Promisesvar promises: an array or plain object containing Promises
The exception is a jqXHR object, which I will name var jqXHR (again, I don't recall ever needing two or more in the same scope).
