Thanks to those who confirmed the ITU text on when leap seconds can be applied.
I've made two small edits to the Wikipedia article to correct parts which were wrong or potentially misleading (plus a slightly tongue-in-cheek remark in the discussion page) However, it's a horrible article and really needs reorganization as some of the paragraphs have suffered serious mission creep. I don't even like the first sentence. "Intercalary" seems wrong to me as a leap second is part of the day it is applied to, not between days. I thought about changing it but decided I might be being a bit blinkered in my definition of "intercalary". Thoughts? Ed.