Related Clues:

• Method of payment for energy is written by person on computer
• Put into a cipher
• Established standards
• Area or zip ending
• Morse's enigma
• Regulatory system on fish numbers
• Moral guidelines broken at GCHQ?
• Make cryptic in French - Napoleonic, perhaps
• The secret language of fish - English!
• Set of rules that's nonsense, fifth-rate
• Make it hard to read the enclosed poem
• Rules lines on carbon
• College poem put in cipher
• Fish sauce -- at last there's a set of rules
• Rules of behaviour one can understand if someone breaks