1. A computer implemented method comprising: storing, in a metadata repository, at least one binary relationship defining an enhancement to a standard meta-object instance, the at least one binary relationship being specified at design time and defining a dependency required to create an enhanced meta-object instance that includes the standard meta-object instance and the enhancement, the standard meta-object instance being provided by a core software platform, the enhanced meta-object comprising at least one additional feature relating to an external software component integrated into the core software platform, wherein the metadata repository comprises system content having a system content format defined by the core software platform and containing system content data that are unique to specific client tenants of a plurality of client tenants, and at least one tenant-specific content item whose tenant-specific content format and tenant-specific content data are defined by and available to only one of the plurality of client tenants; receiving, at run time, a request for a custom instance of a data structure based on the enhanced meta-object instance, the custom instance comprising a meta-object instance extension specified at design time by a service consumer of the core software platform, the service consumer accessing the core software platform via a client tenant of a multi-tenant system comprising an application server providing access for each of a plurality of organizations to one of the plurality of client tenants, each of the plurality of client tenants comprising a customizable, organization-specific version of the core software platform that also integrates business functionality provided by at least the external software provider; generating, at run time, a transitive shell representing the custom instance of the data structure, the generating comprising traversing the at least one binary relationship to create a template meta-object, and applying the meta-object instance extension to the template meta-object to create a current version of the custom instance of the data structure; returning the transitive shell to the service consumer in response to the request; and wherein the storing, receiving, generating and returning are performed by at least one system comprising computer hardware.