"RKB" meaning in Indonesian

{
  "head_templates": [
    {
      "args": {
        "1": "id",
        "2": "noun"
      },
      "expansion": "RKB",
      "name": "head"
    }
  ],
  "lang": "Indonesian",
  "lang_code": "id",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "new classrooms",
          "word": "ruang kelas baru"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "Indonesian entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Initialism of ruang kelas baru (“new classrooms”)."
      ],
      "id": "en-RKB-id-noun-Sn-YZBnk",
      "links": [
        [
          "ruang kelas",
          "ruang kelas#Indonesian"
        ],
        [
          "baru",
          "baru#Indonesian"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "initialism"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ʔɛr ˈka bɛ/"
    }
  ],
  "word": "RKB"
}

{
  "head_templates": [
    {
      "args": {
        "1": "id",
        "2": "noun"
      },
      "expansion": "RKB",
      "name": "head"
    }
  ],
  "lang": "Indonesian",
  "lang_code": "id",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "new classrooms",
          "word": "ruang kelas baru"
        }
      ],
      "categories": [
        "Indonesian entries with incorrect language header",
        "Indonesian initialisms",
        "Indonesian lemmas",
        "Indonesian nouns",
        "Indonesian terms with IPA pronunciation"
      ],
      "glosses": [
        "Initialism of ruang kelas baru (“new classrooms”)."
      ],
      "links": [
        [
          "ruang kelas",
          "ruang kelas#Indonesian"
        ],
        [
          "baru",
          "baru#Indonesian"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "initialism"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ʔɛr ˈka bɛ/"
    }
  ],
  "word": "RKB"
}