I always number my language examples as follows:

(3) a. I finally ate today at almost 1pm...
b. I usually don't eat on game day but I ate today for some reason.



For the number (3) I use the automatic numbering function but the sub-level letters a and b I put them manually. Is there a way to number the letters automatically as well? This would be two level auto numbering. I am using Word 07, but willing to upgrade if I get that function in later versions.