Quoting a Post
There are two ways of replying to a post by quoting it. The first option is to click on the Quote button on the top right-hand side of the relevant post. The second option is to select the Reply button which will take you to the Post reply screen. On this page you can quote a post from the Topic Summary located below the message editor. Simply click on Insert Quote next to the relevant post.
Both of the above options add a link to the original post showing the name of the poster and the date and time of the post. This information is added by attributes in the opening quote tag (author=, link=topic=, date=). The plain Bulletin Board Code quote tag simply quotes the relevant post without any additional information.
You can retain or add the 'author' attribute independently of the full quote function.
http://wiki.simplemachines.org/smf/Posting