Hull classification symbol
The hull classification symbol is assigned to each and every UNSC ship. Different types and sizes of ship have different classification symbols. Placed after the symbol is a number. Each ship of that class gets a different number. This way, the Hull Classification Symbol is a sort of numerical identification system for ships, other than their names.
The symbol based on the hull classification symbol system used by the United States Navy in the 20th and 21st centuries with few differences. The symbols have a few things in common, a symbol beginning with "FF" generally denotes a frigate, "DD" a destroyer, "CL" or "CA" a cruiser, "CV" a carrier, and "BB" a battleship. The rest of the letters vary depending on the type of vessel. There can be dozens of types of each class of vessel.
Hull classification symbols are also extended to Covenant ships; as a way of classifying them.
 List of known symbols
- FFG: Frigate
- ODA: Orbital defense platform