Forum OpenACS Q&A: how to use site-compat and blank-compat templates

Hi,

If I want to customize an OpenACS (or .LRN) site, i. ex. with a different footer or something... Where should I do that in site-master or site-compat?

I haven't found info about how to use (when and why) the blank-compat and site-compat templates, instead of blank-master and site-master.