{
  "alternatives": [
    {
      "id": "I",
      "paths": [
        {
          "function": "liquid fill",
          "from": "delivery connection",
          "to": "selected tank"
        },
        {
          "function": "liquid product supply",
          "from": "tank",
          "to": "dispenser"
        },
        {
          "function": "breathing/vent",
          "from": "tank vapor space",
          "to": "selected vent termination"
        },
        {
          "function": "tank-delivery vapor return",
          "from": "tank vapor space",
          "to": "selected delivery vapor interface"
        }
      ]
    },
    {
      "id": "I+II",
      "inherits_functions_from": "I",
      "added_path": {
        "function": "dispenser vapor return",
        "from": "selected dispenser vapor connection",
        "to": "selected receiving tank vapor connection"
      }
    }
  ],
  "compatibility": "independent alternatives; return paths do not automatically replace tank breathing or share all products",
  "geometry_roles": {
    "vertical": "accessible risers/connections",
    "horizontal": "selected slope and collection destination; section verifies crossover elevations"
  },
  "historical_conditions": "composite steel tank drawings; FRP tank piping described similar, actual tanks/dispensers selected by plans",
  "verification": [
    "materials/joints",
    "dispenser and receiving tank interfaces",
    "adopted emissions/containment basis",
    "vent termination",
    "slope/retained liquid",
    "inspection/removal"
  ],
  "excluded": [
    "recovery efficiency guarantee",
    "unrestricted vent release",
    "utility/control architecture",
    "operating lineup"
  ],
  "numerical_slopes": null
}