"railroad diagram" meaning in English

{
  "forms": [
    {
      "form": "railroad diagrams",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "railroad diagram (plural railroad diagrams)",
      "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"
        }
      ],
      "examples": [
        {
          "ref": "1986, Tom Swan, Mastering Turbo Pascal, Hayden Books, page 8",
          "text": "Figure 1-1 is an example of a railroad diagram, also called a syntax graph. To read a railroad diagram, trace its lines, or tracks, with your finger […]",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A type of diagram used to visualize context-free grammars."
      ],
      "id": "en-railroad_diagram-en-noun-L9EcNX98",
      "links": [
        [
          "diagram",
          "diagram"
        ],
        [
          "context-free grammar",
          "context-free grammar"
        ]
      ],
      "synonyms": [
        {
          "word": "syntax diagram"
        },
        {
          "word": "syntax graph"
        }
      ]
    }
  ],
  "word": "railroad diagram"
}

{
  "forms": [
    {
      "form": "railroad diagrams",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "railroad diagram (plural railroad diagrams)",
      "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"
      ],
      "examples": [
        {
          "ref": "1986, Tom Swan, Mastering Turbo Pascal, Hayden Books, page 8",
          "text": "Figure 1-1 is an example of a railroad diagram, also called a syntax graph. To read a railroad diagram, trace its lines, or tracks, with your finger […]",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A type of diagram used to visualize context-free grammars."
      ],
      "links": [
        [
          "diagram",
          "diagram"
        ],
        [
          "context-free grammar",
          "context-free grammar"
        ]
      ],
      "synonyms": [
        {
          "word": "syntax diagram"
        },
        {
          "word": "syntax graph"
        }
      ]
    }
  ],
  "word": "railroad diagram"
}