| Letter designation | Color |
| A | Light brown |
| IN | Black |
| D | Golden |
| E | Bluish gray |
| G | Green |
| TO | Pink |
| L | Blue |
| M | Dark green |
| N | Brown |
| O | Orange |
| P | Purple |
| R | Red |
| S | Grey |
| T | Dark blue |
| V | Violet |
| W | White |
| X | Light green |
| Y | Yellow |
| Z | Blue |
Note: In the multi-letter designation, the first letter indicates the main color of the insulation, the rest indicate the color of the stripes.