Each new letter pair is announced by the DLT. Each provincial registrar accordingly registers new vehicles under its latest available letter pair until all 9,999 numbers have been exhausted, then moves onto the next series letter. Letters whose appearance may be confused are skipped, and so are letter pairs which form words with bad meanings. For example, the combinations "ชน" and "ตด" are not used, as they form words meaning "crash" and "fart".
