Hi, The update of the core model introduced (at least) 3 new categories within the core scheme, http://schemas.ogf.org/occi/core# : http://schemas.ogf.org/occi/core#resource http://schemas.ogf.org/occi/core#link http://schemas.ogf.org/occi/core#action (The core&model page still use the purl.org scheme urls, update needed) These categories are not defined (as e.g. the resources in the infrastructure document) and thus it is not yet entirely clear which set attributes are associated with the categories. The link category is likely to define "occi.link.source", "occi.link.target" for example. We also have hard-coded attributes in the model, the "title" attribute of Kind, "id" and "summary" of Resource, etc. In short there are two ways an attribute can be defined. Which attributes of the core types should be static and which should be defined by categories? What criteria should determine where an attribute is defined? E.g. should Link source/target be defined in the model or by http://schemas.ogf.org/occi/core#link? regards, Ralf