Hierarchy Items

Records have parents and children. Organizations own subsidiaries, ISO committees spawn subcommittees, control catalogs nest controls inside families. JSON-LD gives you no native way to say any of that, because JSON-LD arrays are unordered (see arrays in the style guide): there's no built-in notion of sort order, lineage, or which parent a child belongs to.

hierarchyItems is the answer. It's a top-level Array property on a Thing, registered in the Shared vocabulary as the HierarchyItem Thing, and that registry entry is the authoritative definition. It sits at the top level deliberately: hierarchy is content relationship data, and coreMetaData stays pure provenance bookkeeping. A record can belong to multiple hierarchies, so the property is an array.

Structure

Each HierarchyItem carries:

• @id: URL. The full unique link to the hierarchy item record.
• elementId: String. A unique and persistent identifier for the hierarchy item record.
• parents: Array of parent references (@id, elementId). Empty for a top-level record. Plural because real hierarchies have records with multiple parents.
• children: Array of child references (@id, elementId). Empty for a record without children. The children listed belong to this item's parental genealogy, just like in real life.
• sortValue: Integer. Sorts the record relative to its siblings. Null when order doesn't matter.
• genealogy: An ordered array of elementIds giving the record's lineage, root first. The trail you follow to trace where a record came from.

Example

{
  "@context": "https://grcschema.org",
  "@type": "Person",
  "@id": "https://grcschema.org/person/87",
  "elementId": 87,
  "name": "Jane Doe",
  "hierarchyItems": [
    {
      "@type": "HierarchyItem",
      "@id": "https://grcschema.org/hierarchy/5/item/123",
      "elementId": 123,
      "parents": [
        {
          "parent": {
            "@id": "https://grcschema.org/person/45",
            "elementId": 45
          }
        }
      ],
      "children": [
        {
          "child": {
            "@id": "https://grcschema.org/person/124",
            "elementId": 124
          }
        },
        {
          "child": {
            "@id": "https://grcschema.org/person/125",
            "elementId": 125
          }
        }
      ],
      "sortValue": 1,
      "genealogy": [12, 45, 123]
    }
  ]
}

One record, one hierarchy membership: Jane sits under record 45, above records 124 and 125, first among her siblings, with a lineage that runs 12 → 45 → 123.