Support and Resistance lines have always been lines that can change roles as a stock breaks through them. But they are not the only ones.

Trend lines, up or down, can do this too. Wow has a great example of it at the moment. There is an up trend line that has been valid support from October 2005 that changed to a valid resistance in July 2008.

On the reverse side there is a down trend line giving resistance from the high in December 2007 that changed roles to support in August 2008.

When doing line analysis, it is always a good idea to keep extending your trend lines, even when a stock breaks through them. They can become a valid line on the other side in the future.

(click on image to enlarge)