Creating a Key Schedule

2 LEVEL SYSTEMS 

Simple Master Key System

The master key symbol consists to TWO letters, AA. The change key numbers are added to the master key letters. The numbers come FIRST for a simple master key system, example: 1AA, 2AA, 3AA, etc.

3 LEVEL SYSTEMS 

Grand Master Key System

The grand master keyset symbol is assigned ONE letter, starting with A. The master keyset symbols under this grand are assigned TWO letters, the first of which will be the same as the grand; AA, AB, AC, etc. are all masters under the grand A. (Caution: Do not use the letters, I, O, Q or X because of the possible confusion with the numbers 1 & O. X is reserved for identifying cross keying.) Change key numbers come AFTER the letters, example: AA1, AA2, AA3, etc.

For master keyset symbols beyond AZ, insert a number between the letters to designate which pass through the alphabet they represent. A2A through A2Z represent the second pass through the alphabet of masters under the Grand A. A3A through A3Z would be the third pass through the alphabet. Change keys under these masters have the numbers suffixed in the usual way A2A1, A2A2, A2A3, etc. 

If a cylinder is to be operated by its change key and the GMK only (No master), the change number is added to the GMK symbol. This is illustrated by the keyset symbol A1 in the schematic shown.

4 LEVEL SYSTEMS 

Great Grand Master Key System

The great grand master is assigned the keyset symbol GGM. The rest of the symbols are the same as those in a 3 level system. 

The grand master keys under the GGM are assigned the keyset symbol of single letters of the alphabet A, B, C, D, etc., starting with A. The master keyset symbols under this grand are assigned TWO letters, the first of which will be the same as the grand; AA, AB, ..., BA, BB, ..., CA, CB, ..., etc. (Caution: Do not use the letters, I, O, Q or X because of the possible confusion with the numbers 1 & O. X is reserved for identifying cross keying.) Change key numbers come AFTER the letters, example: AA1, AA2, AA3, etc 

For masters beyond AZ, insert a number between the letters to designate which pass through the alphabet they represent. A2A through A2Z represent the second pass through the alphabet of masters under the Grand A. A3A through A3Z would be the third pass through the alphabet. Change keys under these masters have the numbers suffixed in the usual way A2A1, A2A2, A2A3, etc. 

If a cylinder is to be operated by its change key and the GGM only (No grandmaster, no master), the change number is added to the GGM keyset symbol. This is illustrated by the keyset symbol GGM1 in the schematic shown. 

SINGLE KEYED DIFFERENT (SKD) (Example: Narcotics Room, Pharmacies) When requirements are such that no other key operates the cylinder (master, other change keys, etc.) they are referred to as “single keyed different” and given the keyset symbol SKD. When more than one SKD is required in a facility, they are numbered SKD1, SKD2, SKD3, etc.

NO MASTER KEY (NMK) 

When keying requirements are such that all higher levels of master keys do not operate the cylinder, the suffix (NMK) is added to the keyset symbol. For example, AA1 (NMK) is operated by the change key AA1 only. Neither the A grand, nor the AA master operate the cylinder. A keyset symbol, AA (NMK) indicates the cylinder to be operated by the AA master only, the A grand does not operate the cylinder  

SELECTIVE MASTER KEYS 

It is often useful in large keying systems to issue a high level master key to maintenance personnel which allows access across all master and grand master key boundaries of a keying system. 

To designate that a lock be operated by a selective master key, suffix the symbol in parentheses to the standard symbol. Example: AA1 (ENG). This must be added every time the selective key is to operate and left off whenever the selective key is NOT to operate. For instance, you may lay out a system in which key AA1 is to operate two different offices. Inside one of them is an electrical cabinet which must be accessible to maintenance personnel carrying the ENG key. That lock must be specified as AA1 (ENG), while the lock for the other office must be specified as AA1. 

Selective master key is a convenience feature which decreases the security of the cylinders it operates and limits the expansion and flexibility of the overall keying system. Each selective master key typically eliminates 20-25% of the capacity of the system where it is used, so it should only be specified when absolutely required. It is recommended that no more than one system-wide selective master key be used within the same system.

CROSS KEYING 

Like selective master keying, cross keying is a convenience feature and will limit the expansion and flexibility of the overall key system. Whenever two or more different change keys such as AA1 and AA2 are both required to operate the same cylinder, the cylinder’s security is reduced. This is called cross keying. When the cross keying occurs under all the same higher levels (MK, GMK, GGMK), such as AA1 and AA2, it is known as controlled cross keying. When you combine keys under different higher levels (MK, GMK, GGMK), such as AA1 and AB1, it is known as uncontrolled cross keying, which you NEVER want to do. 

Convenience may reduce cylinder security and hinder the overall key system expansion. Cross keying usually imposes limits on the flexibility and expansion of the overall keying system. This is especially true of uncontrolled cross keying. For these reasons, it is strongly recommended to allow personnel to carry more than one key. Cross keying should be discouraged whenever possible. However, when cross keying is required, it is specified as follows, and should be summarized at the beginning of each order. It cannot normally be added later. Each cross keyed set should also be limited to keys which are all under the same higher level master keys. Prefix the keyset symbol with the letter X (example: XAA3) All keys which are to operate the cylinder are to be listed following the keyset symbol with the phase “to be operated by” (“TBOB”, “OB”, “operated by” are also common phrases/ abbreviations used. Example: XAA3, operated by AA1, AA2, AA, and A. Note that X is a cylinder designation only. The change keyset would be AA3. 

NOTE: HAGER WILL NOT DO UNCONTROLLED CROSS KEYING DUE TO THE REDUCED SECURITY IT CAUSES