cdfRegistryTest1.json

{
    "@context": "http://schema.org/",
    "@type": "Organization",
    "name": "R2R",
    "contactPoint": {
        "@type": "ContactPoint",
        "contactType": "Administrator",
        "url": "http://www.ldeo.columbia.edu/user/arko",
        "name": "Bob Arko",
        "email": "nemo@nobody.com"
    },
    "url": "http://www.rvdata.us",
    "mainEntityOfPage": [{
            "@type": "DigitalDocument",
            "fileformat": "OGC WxS",
            "keywords": "OGC Wxs",
            "description": "OGC Web Feature and other services",
            "url": "http://api.rvdata.us/gis"
        },
        {
            "@type": "DigitalDocument",
            "fileformat": "OGC CSV",
            "keywords": "OGC CSV",
            "description": "OGC coverage description document",
            "url": "http: //api.rvdata.us/catalog"
        },
        {
            "@type": "DigitalDocument",
            "fileformat": "OGC CSV",
            "keywords": "SPARQL",
            "description": "R2R SPARQL end point",
            "url": "http: //data.rvdata.us/sparql"
        }
    ]
}

what about using the Service class for describing the services instead of mainEntityOfPage?

JSON-LD: https://gist.github.com/ashepherd/562a68ecbd7303c0600602f652241ba7