Hall symbol aliases (property)

{
    "$id": "https://schemas.anyterial.se/defs/v0.1/properties/spacegroups/hall_aliases",
    "$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json",
    "title": "Hall symbol aliases",
    "x-optimade-type": "list",
    "x-optimade-definition": {
        "kind": "property",
        "version": "0.1.0",
        "format": "1.3",
        "name": "hall_aliases",
        "label": "hall_aliases_spacegroups"
    },
    "type": [
        "array",
        "null"
    ],
    "description": "Alternate ASCII Hall symbols or Hall-setting keys associated with the same generated setting.\n\nAliases capture duplicate or equivalent Hall-table forms that identify the same setting in the generated tables.\n\n**Requirements/Conventions**:\n\n- The preferred display symbol is stored in `hall`.\n- Alias values SHOULD NOT be assumed to be unique across all settings without also considering the setting key.",
    "x-optimade-unit": "inapplicable",
    "examples": [
        [
            "A -2yac"
        ],
        [
            "C -2ybc"
        ]
    ],
    "items": {
        "x-optimade-type": "string",
        "type": [
            "string",
            "null"
        ],
        "description": "One alternate symbol string.",
        "x-optimade-unit": "inapplicable"
    }
}