The long and sho arms of chromosomes are designed respectively as:

The sho arm of the chromosome is designated the letter "p" (p for petit in french) and the long arm of the chromosome is designated the letter "q" (the next alphabet to "p"). Ref: Pathologic Basis of Disease, Robbins, 7th Edition, Page 171; Medical Transcription Made Easy By Alok Jha, 2003 Edition, Page 260