"reserved list" meaning in English

{
  "forms": [
    {
      "form": "reserved lists",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "reserved list (plural reserved lists)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A list of officers on half pay who could be called upon in an emergency."
      ],
      "id": "en-reserved_list-en-noun-pBGpyYSJ",
      "links": [
        [
          "officer",
          "officer"
        ],
        [
          "half pay",
          "half pay"
        ],
        [
          "emergency",
          "emergency"
        ]
      ],
      "raw_glosses": [
        "(historical) A list of officers on half pay who could be called upon in an emergency."
      ],
      "tags": [
        "historical"
      ]
    }
  ],
  "word": "reserved list"
}

{
  "forms": [
    {
      "form": "reserved lists",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "reserved list (plural reserved lists)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with historical senses",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A list of officers on half pay who could be called upon in an emergency."
      ],
      "links": [
        [
          "officer",
          "officer"
        ],
        [
          "half pay",
          "half pay"
        ],
        [
          "emergency",
          "emergency"
        ]
      ],
      "raw_glosses": [
        "(historical) A list of officers on half pay who could be called upon in an emergency."
      ],
      "tags": [
        "historical"
      ]
    }
  ],
  "word": "reserved list"
}