With the valuable help of marmot, I am designing new shapes with fixed dimensions. If I write text in these nodes, they are not adapted to the text. I need to eliminate the posibility of writing anything, because I don't need it. Does somebody know the way to do it?
pics. True, they do not have anchors with the same syntax as nodes, but they can have anchors in the sense of prefixed coordinates. If you are just bugged by getting rid of the node contents, you can just addnode contents={}to the style with which you are using the shape.name prefixforpics is currently broken: sourceforge.net/p/pgf/bugs/312pics. Nesting is still broken.