Standardization is required at different levels, first, when the resources are created they must require technologies, policies, and formats that are compatible with what is common in the sector; second, when these resources are included in a repository and must be described, schemes will be used to ensure their easy location and compatibility with other metadata systems; third, when those resources are used and have to be incorporated into different services, repositories, platforms and applications in a given context; and fourth, when the systems involved in an environment have to interoperate with others to fulfill their functions or expand their capabilities.