Using a Google search, I found the following excerpt from a Mario Batali book:
"In Italy double zero (00) is the pasta maker's choice: the 00 refers to
its sift fineness. Since it's hard to come by here, I like to blend 80
percent cake flour and 20 percent all-purpose flour, but if you want to buy
only one type of flour for making fresh pasta which isn't such a tragedy,
buy cake flour. Be sure to avoid "self-rising" cake flour."
I have made both pasta and pizza dough using all-purpose flour and have
been satisfied with the results, but I think I will try the cake
flour/all-purpose flour mix next time.
Jerry Ulett