This is an IVOA Note expressing suggestions from and opinions of the authors. It is intended to share best practices, possible approaches, or other perspectives on interoperability with the Virtual Observatory. It should not be referenced or otherwise interpreted as a standard specification. This is an IVOA Working Draft for review by IVOA members and other interested parties. It is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use IVOA Working Drafts as reference materials or to cite them as other than "work in progress". This is an IVOA Proposed Recommendation made available for public review. It is appropriate to reference this document only as a recommended standard that is under review and which may be changed before it is accepted as a full Recommendation. This document has been reviewed by IVOA Members and other interested parties, and has been endorsed by the IVOA Executive Committee as an IVOA Recommendation. It is a stable document and may be used as reference material or cited as a normative reference from another document. IVOA's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability inside the Astronomical Community. This is an IVOA Proposed Endorsed Note for review by IVOA members and other interested parties. It is appropriate to reference this document only as a Proposed Endorsed Note that is under review and may change before it is endorsed or may not be endorsed. This document is an IVOA Endorsed Note. It has been reviewed and endorsed by the IVOA Technical Coordination Group as a stable, citable document which constitutes valuable information for the IVOA community and beyond. Invalid document status (this cannot happen).