Enjoying the Old SOP! SOP - a thing given or done as a conces- sion of no great value to appease someone whose main concerns or demands are not being met. (ex.: “My agent telephones as a SOP but never finds me work.”) We are actually referring here to the “sequence of progression,” one of the necessary considerations when setting up a master keyed system. SOP (sequence of progression) - n. the order in which bitting positions are pro- gressed to obtain change key combinations Depending on the progression type (soon to be discussed), parity may be an issue. Parity parity - n. the property of being either even or odd, as the depth number of a bitting in a combination, or the possible progressives in a given position of a two- step progression Odd numbers (1, 3, 5, 7, 9) Even numbers (0, 2, 4, 6, 8) Used with two-step progression type Parity is used when the increment sys- tem is usually less than .023” (not used with single-step) Can we ever use “altered parity” (not like altered reality) — a type of mixture? In some situations, yes. It’s common in the one-step type of progression where odd and even are used in one column, as they all play well together. It does not fare well in two-step where either odd or even are used in any one column. Again, there are situations when parity is mixed in other kinds of systems, but that’s more advanced than we need worry about right now. Notice in our KBA example (Figure 5) that column two and column five have no numerals below the TMK. That’s because WWW.ALOA.ORG Figure 5. The top master key (TMK) bitting is perched at the top of the KBA. Below it are columns of numbers. At the bottom is a row of letters referred to as the sequence of progression (SOP). in those particular chambers of the lock, no master pins will be used. Therefore, they are referred to as “held constant” or “held.” The TMK bitting numeral for those columns will “fall down” into the various change key bittings as they are se- quentially created. That’s where the TMK and the CK will “share,” occurring in the rotating constant method. They never share in the TPP method and remain as isolated as can be. But, once we have all of these bittings, can we just use them as we please? No way, José! There are four basic kinds of bittings, and one of them involves MACS. Let’s look at that first. MACS maximum adjacent cut specification - n. the maximum allowable difference between adjacent cut depths If a manufacturer has a MACS of 5, then going beyond that difference in ad- jacent key depths is not recommended. Example: Placing a #7 cut next to a #2 cut is allowable because the difference is 5. However, a #1 cut next to a #7 cut exceeds the MACS and is prohibited. Also, another factor to consider in es- tablishing a master key system is “incre- ment.” Depending on the manufacturer, the key system’s increment will use either a single-step drop or a two-step drop. This is referred to as progression types. If a sin- gle-step progression (one-step) is used, all numbers below the TMK will be used in each column to create change keys, based on the manufacturer system specs. If a two-step progression is used, every other numeral will be used — that odd-even thing again called parity. In the previous KBA example, parity is maintained. So, you guessed it: That was a two-step system. See how well you are learning! Kinds of Bittings Bittings are not all created equal, though that’s what your school teachers may want you to think. There are four basic classes JULY/AUGUST 2017 KEYNOTES 45
