{
    "properties": {
        "displayName": "Use match condition on tag value.",
        "description": "Enforce a text pattern on tag value.",
        "mode": "All",
        "policyRule": {
            "if": {
                "not": {
                    "field": "tags.date",
                    "match": "##-???-####"
                }
            },
            "then": {
                "effect": "deny"
            }
        }
    }
}