The following are FCC Standards for slate letter codes. Note that the letters I and O are not used because they too closely resemble the numbers 1 and 0.
| A ALPHA | B BRAVO | C CHARLIE |
| D DELTA | E ECHO | F FOXTROT |
| G GOLF | H HOTEL | J JULIETTE |
| K KILO | L LIMA | M MIKE |
| N NOVEMBER | P POPPA | Q QUEBEC |
| R ROMEO | S SIERRA | T TANGO |
| U UNIFORM | V VICTOR | W WHISKEY |
| X X-RAY | Y YANKEE | Z ZULU |
After “Z”, the lettering goes as follows:
- AA, AB, AC, AD…AZ
- BA, BB, BC, BD, …BZ and so on.