"15mb" meaning in Translingual

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  "etymology_text": "From Italian quindicesima bassa (“fifteenth lower”), by analogy with 15ma interpreted as an abbreviation of Italian quindicesima alta (“fifteenth higher”).",
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          "kind": "other",
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        {
          "kind": "other",
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        },
        {
          "kind": "topical",
          "langcode": "mul",
          "name": "Music",
          "orig": "mul:Music",
          "parents": [
            "Art",
            "Sound",
            "Culture",
            "Energy",
            "Society",
            "Nature",
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            "Fundamental"
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      "glosses": [
        "An instruction to play two octaves lower than indicated."
      ],
      "id": "en-15mb-mul-symbol-2pnrjDIf",
      "links": [
        [
          "music",
          "music"
        ],
        [
          "octave",
          "octave"
        ]
      ],
      "raw_glosses": [
        "(music, very rare) An instruction to play two octaves lower than indicated."
      ],
      "related": [
        {
          "word": "15ma"
        },
        {
          "word": "8va"
        },
        {
          "word": "8vb"
        }
      ],
      "tags": [
        "rare"
      ],
      "topics": [
        "entertainment",
        "lifestyle",
        "music"
      ],
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        "15mb"
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  "pos": "symbol",
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      "word": "8va"
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      "glosses": [
        "An instruction to play two octaves lower than indicated."
      ],
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          "octave"
        ]
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        "(music, very rare) An instruction to play two octaves lower than indicated."
      ],
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