Specification Sheet

5
K E Y I N G S Y S T E M S
H O W T O S P E C I F Y M A S T E R K E Y I N G
When all higher levels of master keys are to be disallowed, sufx
(NMK) to the symbol of the key which is to operate. This means
“not master keyed.” Cylinder 1AA(NMK) is operated by 1AA
only. The AA master is blocked from operation.
2- and 3-Level Master Keying Systems
To Specify a Simple Master Key System (2 Levels of Keying)
The master key symbol consists of TWO letters, such as AA. The
change key numbers are added to the master key letters. The
numbers come FIRST: 1AA, 2AA, 3AA, etc.
When locks are required which are not operated by the master
key or other change keys in the system, they are referred to as
“single keyed” and given symbols SKD1, SKD2, etc.
AA
1AA 2AA 3AA SKD1
When locks are required which are not operated by ANY master
keys or other change keys in the system, they are referred to as
“single keyed” and given symbols SKD1, SKD2, etc.
When all higher levels of master keys are to be disallowed, sufx
(NMK) to the symbol of the key which is to operate. This means
“not master keyed” and can be applied to any level in the system.
Cylinder AA1(NMK) is operated by AA1 only. The AA master
and A grand are blocked from operation.
Cylinder AA(NMK) would be operated by the AA master only.
Grand A does not operate.
2- and 3-Level Master Keying Systems
To Specify a Grand Master Key System (3 Levels of Keying).
The grand master is assigned any ONE letter, such as A. The
master keys under this grand are assigned TWO letters, the rst
of which must be the same as the grand: AA, AB, AC, etc. are
all masters under grand A. Masters BA, BB, BC, etc. are all
under grand B. Caution: Do not use the letters I or O because
of possible confusion with the numerals 1 and 0, respectively.
Change key numbers come after the letters.
For master keys beyond AZ, insert a number between the letters
to designate which pass through the alphabet they represent.
A2A through A2Z represents the second pass of masters under
grand A. A3A through A3Z would be the third. Change keys
under these masters have the numbers sufxed in the usual way:
A2A1, A2A50, etc.
If the cylinder is to be operated by its change key and nothing
lower than the single lettered GMK, the change number is added
to the GMK symbol. This is illustrated by the example A1 in the
schematic shown.
AA
AA1 AA3
AB1
AB2
A
AA2
A1
SKD1
AB