Last seen in:
- Canadiana - Dec 16 2019
- The Guardian - Quick crossword No 15,425 - Oct 15 2019
- The Times - Concise - Sunday Times Concise No 1571
- Canadiana - Feb 26 2018
- Premier Sunday - King Feature Syndicate - Aug 27 2017
- The Telegraph - QUICK CROSSWORD NO: 28,462 - Jun 24 2017
- Eugene Sheffer - King Feature Syndicate - Jun 21 2016
- The Telegraph - QUICK CROSSWORD NO: 27,892 - Aug 28 2015
- Newsday.com - Dec 3 2014
- The Telegraph - QUICK CROSSWORD NO: 26,804 - Mar 3 2012
Related Clues:
- Secret symbols
- Procedure or system of rules
- Cryptographic system
- System of rules
- System of signals
- Secret system of letters. words etc
- Cipher — set of principles
- Rule book
- Render unreadable, in a way
- Building inspector's expertise
- Professional to telephone, reportedly, on top of watching Ps and Qs
- Cryptologist's interest
- In favour of getting to Colonel for agreement
- Be a computer programmer
- Internet expert Lawrence Lessig's subject