Related Clues:

• Telephone area ___
• Zip ___
• Cryptographers break it
• Pearl Jam's 4th "No ___"
• Do some programming
• Etiquette of fish knife's last
• Area ___ (phone number start)
• Navajo ___ talkers of WWII
• Builder's concern
• ___ of silence
• Program instruction
• What to cipher
• Actor died having lost odd set of principles
• Law lord who ran to catch duke
• It's key to border's commodities trade