"supplementary relative clause" meaning in English

{
  "forms": [
    {
      "form": "supplementary relative clauses",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "head": "supplementary relative clause"
      },
      "expansion": "supplementary relative clause (plural supplementary relative clauses)",
      "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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Grammar",
          "orig": "en:Grammar",
          "parents": [
            "Linguistics",
            "Language",
            "Social sciences",
            "Communication",
            "Sciences",
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2024, Geoffrey K. Pullum, The Truth About English Grammar, Polity Press, →ISBN, page 112:",
          "text": "Supplementary relative clauses (which other books call “appositive relatives” or “non-restrictive relatives”) are optional parenthetical interruptions of sentences. They can always be left out without changing the main assertion (though the ancillary information they contribute will be gone). The most important thing to remember about them in writing is that they must be separated off by punctuation, typically commas: The duke, [who the organizers had hoped __ would present the award], was unable to attend owing to illness.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Synonym of non-restrictive relative clause."
      ],
      "id": "en-supplementary_relative_clause-en-noun-aIxC~x~V",
      "links": [
        [
          "grammar",
          "grammar"
        ],
        [
          "non-restrictive relative clause",
          "non-restrictive relative clause#English"
        ]
      ],
      "raw_glosses": [
        "(grammar) Synonym of non-restrictive relative clause."
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "non-restrictive relative clause"
        }
      ],
      "topics": [
        "grammar",
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "word": "supplementary relative clause"
}

{
  "forms": [
    {
      "form": "supplementary relative clauses",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "head": "supplementary relative clause"
      },
      "expansion": "supplementary relative clause (plural supplementary relative clauses)",
      "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 quotations",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Grammar"
      ],
      "examples": [
        {
          "ref": "2024, Geoffrey K. Pullum, The Truth About English Grammar, Polity Press, →ISBN, page 112:",
          "text": "Supplementary relative clauses (which other books call “appositive relatives” or “non-restrictive relatives”) are optional parenthetical interruptions of sentences. They can always be left out without changing the main assertion (though the ancillary information they contribute will be gone). The most important thing to remember about them in writing is that they must be separated off by punctuation, typically commas: The duke, [who the organizers had hoped __ would present the award], was unable to attend owing to illness.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Synonym of non-restrictive relative clause."
      ],
      "links": [
        [
          "grammar",
          "grammar"
        ],
        [
          "non-restrictive relative clause",
          "non-restrictive relative clause#English"
        ]
      ],
      "raw_glosses": [
        "(grammar) Synonym of non-restrictive relative clause."
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "non-restrictive relative clause"
        }
      ],
      "topics": [
        "grammar",
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "word": "supplementary relative clause"
}