"ΔΠΑΒ" meaning in Greek

{
  "forms": [
    {
      "form": "DPAV",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "2": "noun"
      },
      "expansion": "ΔΠΑΒ • (DPAV)",
      "name": "head"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Greek entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "ISBN (International Standard Book Number)"
      ],
      "id": "en-ΔΠΑΒ-el-noun-iR3mENXO",
      "links": [
        [
          "ISBN",
          "ISBN"
        ],
        [
          "International Standard Book Number",
          "International Standard Book Number"
        ]
      ]
    }
  ],
  "word": "ΔΠΑΒ"
}

{
  "forms": [
    {
      "form": "DPAV",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "2": "noun"
      },
      "expansion": "ΔΠΑΒ • (DPAV)",
      "name": "head"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Greek entries with incorrect language header",
        "Greek lemmas",
        "Greek nouns"
      ],
      "glosses": [
        "ISBN (International Standard Book Number)"
      ],
      "links": [
        [
          "ISBN",
          "ISBN"
        ],
        [
          "International Standard Book Number",
          "International Standard Book Number"
        ]
      ]
    }
  ],
  "word": "ΔΠΑΒ"
}

{
  "called_from": "form_descriptions/1698",
  "msg": "unrecognized head form: Διεθνής Πρότυπος Αριθμός Βιβλίου (δieθnís prótipos ariθmós vivlíou)",
  "path": [
    "ΔΠΑΒ"
  ],
  "section": "Greek",
  "subsection": "noun",
  "title": "ΔΠΑΒ",
  "trace": ""
}