outpostmm

I'm a little confused trying to get the auth.net AIM module set up with osCommerce 2.3.1. I'm not very familiar with osCommerce, I'm trying to get this set up for a friend. First, about the transaction method option - the options are Authorization or Capture. Why is it one or the other, why can't we both authorize and capture the transaction at once? Do people usually do authorize-only, and then have to go back and manually capture each transaction?