Does Anybody Know How Rune Pages Work in Pro Play?

What I mean is, how do the players select which runes to use before they play? For masteries it makes sense since most people will just make a page in the ~60 seconds they have after champs are chosen, but what about the runes? Do they just load into the games with a bunch of pages for the meta champs, or are they allowed to make their own rune pages in champ select? Just curious, in case anybody knows.