When we started label-schema, the intention was to provide a single set of common labeling conventions for container images. Since the OCI has defined a parallel set of similar conventions in the OCI Image Spec (known as annotations rather than labels) it makes sense to consolidate efforts in one place.
This project is no longer actively maintained. Visit http://label-schema.org for more information about the legacy label-schema project, and go to the OCI Image Spec for future label definitions.