Andy, you asked about whether a Mixin related to another Mixin will inherit the attributes. Please look at OCCI Core page 9: "Mixin Relationships A Mixin instance MAY be related to another Mixin instance for type classification purposes. For example a set of operating system templates, implemented as Mixin instances, could be related to an “OS-template” Mixin in order to help identification. Attributes and Actions defined by different Mixin instances are combined when Mixin relationships are present. ^^^^^^^^^^^ Therefore a resource instance associated with a particular Mixin will receive the additional capabilities defined by any related Mixin instances as well as those defined by the Mixin associated." Does this cover what you were after? Maybe it is unclear that "capabilities" refer to attributes as well? regards, Ralf