CPL Master Key System Architecture 3 — Questions and Answers
Question 1: In a master key system bitting list, what does the column labeled 'MK' typically represent?
- The mechanical key cut sequence
- The master key bitting for that group (Correct answer)
- The minimum key blank tolerance
- The master key identification number
Correct answer: The master key bitting for that group
The 'MK' column in a bitting list records the master key bitting depths used as the controlling bitting for a group of change keys.
Question 2: What is 'maison keying'?
- A system where one key opens many locks but each lock has its own unique key (Correct answer)
- A system where all locks use the same change key
- A system where the grandmaster key is held by property management
- A system where locks are re-keyed seasonally
Correct answer: A system where one key opens many locks but each lock has its own unique key
Maison keying (also called 'hotel keying') allows a single entry key to open multiple units, while each unit also has its own individual key.
Question 3: When designing a master key system, what does 'total bitting list' (TBL) analysis help prevent?
- Key duplication by unauthorized locksmiths
- Duplicate key cuts that would cause unintended cross-keying (Correct answer)
- Worn keys from operating multiple locks
- High-security cylinders from being installed
Correct answer: Duplicate key cuts that would cause unintended cross-keying
A total bitting list analysis compiles all key bittings in the system to identify and eliminate duplicate or conflicting bitting combinations that could cause cross-keying.
Question 4: What is the role of a 'sub-master key' in a tiered master key system?
- It operates only emergency exit locks
- It operates a defined subset of locks within a master key group (Correct answer)
- It serves as a backup to the grandmaster key
- It overrides the change key but not the master key
Correct answer: It operates a defined subset of locks within a master key group
A sub-master key is positioned below the master key in the hierarchy, controlling a specific subset of locks within a larger master key group.
Question 5: In a six-pin cylinder master key system, what is the maximum theoretical number of usable change key combinations using a progression increment of 1 across depths 1–9?
- 531,441
- 9^6 minus unusable bittings (Correct answer)
- 720
- 59,049
Correct answer: 9^6 minus unusable bittings
While 9^6 = 531,441 combinations exist mathematically, real-world usability is reduced by MACS violations, cross-keying conflicts, and progression rules, leaving far fewer usable bittings.
Question 6: What does 'MACS' stand for in key system design?
- Master Access Control Standard
- Maximum Adjacent Cut Specification (Correct answer)
- Minimum Allowable Cut Spacing
- Master Architecture Coding System
Correct answer: Maximum Adjacent Cut Specification
MACS stands for Maximum Adjacent Cut Specification, defining the greatest allowable difference between two adjacent cuts on a key to ensure the key can be cut and operate properly.
Question 7: Which of the following is a primary disadvantage of adding more levels to a master key hierarchy?
- Keys become physically longer
- More master pins are required, increasing vulnerability to manipulation and cross-keying (Correct answer)
- The grandmaster key can no longer open all locks
- The system requires electronic override components
Correct answer: More master pins are required, increasing vulnerability to manipulation and cross-keying
Each additional hierarchy level requires more master wafers per cylinder, increasing the number of false shear lines and making the lock easier to pick and more prone to cross-keying.
CPL Master Key System Architecture 3
In a master key system bitting list, what does the column labeled 'MK' typically represent?