It's open to interpretation. You can use any commercially loaded hardball round for practice, they are all made to SAAMI specs. As long as it functions reliably in in your firearm, it really doesnt matter. Keep in mind that guns are inherently more accurate then you can hold them anyway. For duty/defense, I generally will only carry ammunition that has passed the FBI test protocol and proven itself reliable. In my experience, Speer Gold Dot has performed the best and is what's loaded in my defensive weapons. YMMV.

Here is the FBI ammunition test protocol: http://greent.com/40Page/general/fbitest.htm

Here's the listings:
http://www.ar15.com/content/page.html?id=237

FYI, I added a second link to my original post.

Black Talon 9mm Hollow points.

Ball ammo for auto's and wadcutters for revolvers are fine for practice. The idea is that you MUST practice and practice often so that shooting becomes very natural for you. In my personal protection weapons I carry jacketed hollow points in the Makrov and Federal Hydro-shock in the .45. One of those rounds hit you, you will go down and it is doubtful you will ever get back up again. No sense in playing if deadly force is required. I also have my stub .38 loaded with +P hollow-points. I keep a shotgun loaded with 1st round magnum 00 buck and 2nd rd 1oz slug and then back to 00 buck.