# INT-1 Symbol Reference — Sections P (Lights) and Q (Buoys / Beacons)

## INT-1 Section Q — Buoy Shapes

| Code | Shape | Notes |
|------|-------|-------|
| Q20  | Conical buoy (nun buoy) | Pointed top; IALA Region B = green starboard |
| Q21  | Can buoy (cylindrical)  | Flat top; IALA Region B = red port |
| Q22  | Spherical buoy          | Ball-shaped |
| Q23  | Pillar buoy             | Any superstructure on small platform (lantern, topmark, radar) |
| Q24  | Spar buoy (spindle)     | Long thin pole, nearly vertical |
| Q25  | Barrel buoy (tun)       | Cask / drum shape |
| Q26  | Major floating light    | LANBY / light vessel; large platform with full light structure |

---

## INT-1 Section Q — IALA Lateral Marks

### IALA Region A (Europe, Africa, Asia, Australasia)
| Mark         | Colour   | Shape       | Topmark    | Light        |
|--------------|----------|-------------|------------|--------------|
| Port (left)  | Red      | Can/Cylinder| Red can    | Red: any rhythm |
| Starboard (right) | Green | Conical   | Green cone point up | Green: any rhythm |
| Preferred channel to stbd (modified port) | Red + green band | Can | Red can | Fl(2+1)R |
| Preferred channel to port (modified stbd) | Green + red band | Conical | Green cone up | Fl(2+1)G |

### IALA Region B (Americas, Philippines, Japan, South Korea)
| Mark         | Colour   | Shape       | Topmark    | Light        |
|--------------|----------|-------------|------------|--------------|
| Port (left)  | Green    | Can/Cylinder| Green can  | Green: any rhythm |
| Starboard (right) | Red | Conical    | Red cone point up | Red: any rhythm |
| Preferred channel to stbd (modified port) | Green + red band | Can | Green can | Fl(2+1)G |
| Preferred channel to port (modified stbd) | Red + green band | Conical | Red cone up | Fl(2+1)R |

> S-57 attribute CATLAM: 1=port, 2=starboard, 3=preferred channel to stbd, 4=preferred channel to port

---

## INT-1 Section Q — Cardinal Marks (IALA, same both regions)

| Mark       | Colour (top/bottom)   | Topmark              | Light                  | Meaning |
|------------|-----------------------|----------------------|------------------------|---------|
| North (N)  | Black over Yellow     | 2 cones point UP     | VQ or Q (continuous)   | Pass to the north |
| East (E)   | Black / Yellow / Black| 2 cones base-to-base | VQ(3) 5s or Q(3) 10s   | Pass to the east |
| South (S)  | Yellow over Black     | 2 cones point DOWN   | VQ(6)+LFl 10s or Q(6)+LFl 15s | Pass to the south |
| West (W)   | Yellow / Black / Yellow| 2 cones point-to-point | VQ(9) 10s or Q(9) 15s | Pass to the west |

> S-57 attribute CATCAM: 1=N, 2=E, 3=S, 4=W

---

## INT-1 Section Q — Other Special Marks

### Isolated Danger Mark (S-57 layer: BOYISD / BCNISD)
- Colour: Black with one or more red horizontal bands
- Topmark: 2 black spheres (one above the other)
- Light: Fl(2) White
- Meaning: Isolated danger with navigable water all around

### Safe Water Mark (S-57 layer: BOYSAW)
- Colour: Red and white vertical stripes
- Shape: Spherical, pillar, or spar
- Topmark: Single red sphere
- Light: Iso W, Oc W, LFl W 10s, or Morse "A" (. ―) W
- Meaning: Safe water on all sides (mid-channel, landfall)

### Special Purpose Mark (S-57 layer: BOYSPP)
- Colour: Yellow
- Shape: Any (X topmark optional)
- Light: Yellow, any rhythm not used for other marks
- Meaning: Special feature (traffic separation, spoil ground, cable, military, etc.)

### Emergency Wreck Marking Buoy (IALA / AISM)
- Colour: Blue and yellow vertical stripes (alternating)
- Shape: Pillar or spar
- Topmark: Single upright yellow cross
- Light: Al.Bu.Y 3s (alternating blue and yellow) or VQ(4) Y + VQ(4) Bu
- AIS: AtoN transponder transmitting
- Meaning: Newly discovered dangerous wreck

---

## INT-1 Section P — Light Characters

| Abbreviation | Full name          | Description |
|--------------|--------------------|-------------|
| F            | Fixed              | Continuous steady light |
| Oc           | Occulting          | Light longer than darkness; Oc(2) = group of 2 eclipses |
| Iso          | Isophase           | Equal light and dark periods |
| Fl           | Flashing           | Single flash, dark > light; Fl(3) = group of 3 |
| LFl          | Long Flash         | Flash ≥ 2 seconds |
| Q            | Quick              | 50–60 flashes/min; Q(6) = group of 6 |
| VQ           | Very Quick         | 100–120 flashes/min |
| UQ           | Ultra Quick        | ≥ 160 flashes/min |
| Mo           | Morse code         | Dots and dashes; Mo(A), Mo(U), etc. |
| FFl          | Fixed + Flashing   | Steady light with superimposed flashes |
| Al           | Alternating        | Changes colour; Al.WR = alternates White/Red |

### Light Colours
| Code | Colour  |
|------|---------|
| W    | White   |
| R    | Red     |
| G    | Green   |
| Bu   | Blue    |
| Vi   | Violet  |
| Y    | Yellow  |
| Or   | Orange  |
| Am   | Amber   |

### S-57 LITCHR Numeric Codes (used in ENC data)
| Code | Abbreviation |
|------|-------------|
| 1    | F           |
| 2    | Fl          |
| 3    | LFl         |
| 4    | Q           |
| 5    | VQ          |
| 6    | UQ          |
| 7    | Iso         |
| 8    | Oc          |
| 9    | IQ (interrupted quick) |
| 10   | IVQ (interrupted very quick) |
| 11   | IUQ (interrupted ultra quick) |
| 12   | Mo          |
| 13   | FFl         |
| 14   | Fl+LFl      |
| 15   | Oc+Fl       |
| 25   | Al.Oc       |
| 26   | Al.LFl      |
| 27   | Al.Fl       |
| 28   | Al.Grp      |

### S-57 COLOUR Numeric Codes
| Code | Colour   |
|------|----------|
| 1    | White (W) |
| 2    | Black (K) |
| 3    | Red (R)   |
| 4    | Green (G) |
| 5    | Blue (Bu) |
| 6    | Yellow (Y) |
| 7    | Grey (Gy) |
| 8    | Brown (Br) |
| 9    | Amber (Amb) |
| 10   | Violet (Vi) |
| 11   | Orange (Or) |
| 12   | Magenta (Mg) |

---

## INT-1 Section P — Leading Lines / Range Lights

| Code    | Description |
|---------|-------------|
| P20.1   | Leading lights / range lights: two lights (front and rear) forming a transit. Solid line on chart = the recommended track. |
| P20.2   | Any two objects in line constitute a transit bearing. |

Leading line light: has the S-57 attribute ORIENT (bearing in True degrees). The backend emits a LDLINE GeoJSON LineString feature projected along that bearing for rendering.
