[GiNaC-list] indexed structure, is possible???

Hi, I am working in a kind of covariant derivative. I started with a structure, like in page 81 of tutorial: covdiff(argument,index) I implemented distributive, Leibniz rule, etc.. But I would like to make GiNac threat this structure like a indexed object ( metric tensor could rise indexes, etc). Is there a function option in the definition of structure or a TINFO option? Thanks for all Marco ------------------------------------------------- This mail sent through IMP: http://horde.org/imp/