playing around with this and @jpcs parser.xq, yes dashes ....

gistfile1.json

{
    "p-pipeline": [
        {
            "name": "my-pipeline",
            "p-import": "../test.xpl",
            "p-source": {
                "sequence": false
            },
            "p-results": {},
            "myuri": "http://www.example.org/test.xslt",
            "p-xslt": {
                "stylesheet-href": myuri
            },
            "p-step": {
                "p-type": "xslt",
                "stylesheet-href": ""
            },
            "p-group": [
                {
                    "p-identity": {}
                }
            ],
            "p-choose": [
                {
                    "test": "1 = 1 ",
                    "p-xslt": {}
                },
                {
                    "other-pipe": {}
                }
            ]
        },
        {
            "name": "other-pipeline",
            "p-count": {"limit":5}
        }
    ]
}