{
  "threads": [
    {
      "thread": "M3",
      "standard": "ISO 261:1998",
      "pitch_mm": 0.5,
      "major_mm": 3.0,
      "lengths": [
        {
          "label": "6 mm",
          "mm": 6.0
        },
        {
          "label": "8 mm",
          "mm": 8.0
        },
        {
          "label": "10 mm",
          "mm": 10.0
        }
      ],
      "tap_drill_mm": 2.5,
      "eis_thread": true
    },
    {
      "thread": "M2.5",
      "standard": "ISO 261:1998",
      "pitch_mm": 0.45,
      "major_mm": 2.5,
      "lengths": [
        {
          "label": "6 mm",
          "mm": 6.0
        },
        {
          "label": "8 mm",
          "mm": 8.0
        },
        {
          "label": "10 mm",
          "mm": 10.0
        }
      ],
      "tap_drill_mm": 2.05,
      "eis_thread": false
    },
    {
      "thread": "#4-40 UNC",
      "standard": "ASME B1.1-2019",
      "pitch_mm": 0.635,
      "major_mm": 2.845,
      "lengths": [
        {
          "label": "1/4 in",
          "mm": 6.35
        },
        {
          "label": "5/16 in",
          "mm": 7.9375
        },
        {
          "label": "3/8 in",
          "mm": 9.525
        }
      ],
      "tap_drill_mm": 2.26,
      "eis_thread": false
    }
  ],
  "head": {
    "form": "pan",
    "drives": [
      "cross recess H",
      "cross recess Z",
      "hexalobular"
    ],
    "standards": [
      "ISO 7045:2011",
      "ISO 14583:2011",
      "ASME B18.6.3-2013"
    ],
    "diameter_max_mm": 7.0
  },
  "materials": [
    "steel, zinc plated",
    "steel, black finish",
    "stainless steel A2"
  ],
  "engagement_threads_min": 3,
  "panel_thickness_mm": {
    "min": 1.6,
    "max": 2.0
  },
  "notes": "The thread is M3 (EIS-RAIL-005). M2.5 and #4-40 UNC rows are subrack hardware outside EIS, kept for the length-window tool and Annex A.3; they are informative. Length window: t_max + seat + 3P <= L <= t_min + D. seat is the depth of the insert's front face behind the mounting face; D is the depth of the screw cavity behind the mounting face; P is the thread pitch. A screw also passes any throat in front of the insert.",
  "provenance": {
    "threads": {
      "id": "EIS-RAIL-005",
      "kind": "eis",
      "note": "M3"
    },
    "threads.pitch_mm": {
      "id": "EIS-RAIL-006",
      "kind": "quoted",
      "source": "ISO 261:1998 (M3 0.5 mm, M2.5 0.45 mm); ASME B1.1-2019 (#4-40, 40 threads per inch)"
    },
    "threads.major_mm": {
      "id": "EIS-RAIL-007",
      "kind": "quoted",
      "source": "ISO 261:1998 nominal diameters; ASME B1.1-2019 basic major diameter 0.112 in"
    },
    "threads.lengths": {
      "kind": "informative",
      "note": "Three lengths per thread; every length is the pick for at least one catalog rail in Annex A"
    },
    "threads.tap_drill_mm": {
      "kind": "informative",
      "source": "Schroff EuropacPRO p. 6.37 (M3 2.5 mm, M2.5 2.05 mm); No. 43 drill, 0.0890 in, for #4-40",
      "note": "Recommended practice; Annex A"
    },
    "head.form": {
      "kind": "informative",
      "source": "ISO 7045:2011; ISO 14583:2011; ASME B18.6.3-2013",
      "note": "Recommended practice; Annex A"
    },
    "head.diameter_max_mm": {
      "id": "EIS-RAIL-010",
      "kind": "eis",
      "note": "Within the narrowest catalog rail face, 3.7 mm past the hole center (Vector T-strut, Annex A), so the head bears on the panel and the rail face of every catalog rail"
    },
    "materials": {
      "kind": "informative",
      "note": "Recommended practice; Annex A"
    },
    "engagement_threads_min": {
      "id": "EIS-RAIL-008",
      "kind": "eis"
    },
    "length_window": {
      "id": "EIS-RAIL-009",
      "kind": "calculated",
      "from": [
        
        "EIS-PANEL-004",
        "EIS-RAIL-006",
        "EIS-RAIL-008"
      ]
    },
    "enclosure_states_screw": {
      "id": "EIS-RAIL-011",
      "kind": "eis"
    }
  }
}