Maximal subgroup type (property)

{
    "$id": "https://schemas.httk.org/defs/v0.1/properties/transformations/subgroup_type",
    "$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json",
    "title": "Maximal subgroup type",
    "x-optimade-type": "string",
    "x-optimade-definition": {
        "kind": "property",
        "version": "0.1.0",
        "format": "1.3",
        "name": "subgroup_type",
        "label": "subgroup_type_transformations"
    },
    "type": [
        "string"
    ],
    "description": "International Tables maximal subgroup class.\n\nThe value is `t` for a translationengleiche subgroup and `k` for a klassengleiche subgroup.\nThe field is omitted for identity embeddings, for general subgroups that lose both translations and point symmetry, and for records that are not subgroup embeddings.\nIts presence does not by itself certify maximality; the relation table containing the record supplies that information.\n\nA translationengleiche subgroup retains the complete translation lattice and loses point symmetry: `i_T = 1`, `i_P > 1`.\nA klassengleiche subgroup retains the point group and loses translations: `i_P = 1`, `i_T > 1`.\nFor a maximal proper subgroup these are the alternatives; a subgroup losing both is not represented by either value.\nThe underlying t/k classification describes what symmetry is lost and does not by itself prove that an embedding is maximal.",
    "enum": [
        "t",
        "k"
    ],
    "x-optimade-unit": "inapplicable",
    "examples": [
        "k",
        "t"
    ]
}