CS-4OAK.
A CS-4OAK M 4x4x44xx M is any four of the same number within the FSN.

CS-Quad.
A CS-QUAD M xxx4444x M is any four of the same number grouped.

CS-Random 4OAK.
CS-Random 4OAK is any four of the same number anywhere within the serial number as long as it does not make a CS-Quad.

CS-Leading, Center, and Trailing Quads.
CS-Leading, Center, and Trailing Quads are any four of the same number grouped together anywhere within the FSN. Those that start at position 1 are CS-Leading Quads. Those that start in position 2, 3, and 4 are CS-Center Quads. Those that start in position 5 are CS-Trailing Quads.

CS-Double Quad.
CS-Double Quad M 11114444 M are two CS-Quads in sequence and both CS-Quads must be group.

CS-Random Double 4OAK.
CS-Random Double 4OAK M 45554445 M. In a CS-Double 4OAK there are 2 CS-4OAKs in any position.

CS-Quad in Quad.
In a CS-Quad in Quad, there is a CS-Quad and a CS-4OAK. The CS-Quad is grouped and contained within the CS-4OAK. This is also a CS-Binary M 55544445 M.

CS-Quad in Triple.
CS-Quad in Triple is a CS-Quad within a 3OAK M x3344443 M. The CS-Quad must be within the CS-3OAK.

CS-Random Quad in Triple.
With a CS-Random Quad in Triple there is a CS-4OAK inside the CS-Triple and the random digit or one of the CS-3OAK may be inside as well M 34x44433 M.

CS-Double Double.
In a CS-Double Double, there are two split CS-Quads, and the splits must be paired. CS-Double Double M 99559955 M the first part of the first split quad starts at position 1, the second part starts at position 5 while the second split quad starts at position 3, and the second part starts at position 7.

CS-Triple in Quad.
In CS-Triples in Quads, there is a CS-Triple within a CS-4OAK.

CS-Random Triple in Quad.
CS-Random Triple in Quad is a CS-3OAK and CS-4OAK in any position as long as the CS-3OAK is surrounded by the CS-4OAK.

CS-Quad and Pairs.
CS-Quad and Pairs is a CS-Quad and two CS-Pairs, and the CS-Pairs are different numerals from the other CS-Pair and the CS-Quad.

CS-Random Quad and Pairs.
CS-Random Quad and Pairs M 41142424 M is any CS-4OAK and any two CS-2OAKs in any position.

CS-Pairs in Quad.
A CS-Pairs in Quad must contain a CS-4OAK and two CS-Pairs and two digits of the CS-4OAK must be at position 1 and position 8, M 44114224 M.

CS-Quads and Triples.
CS-Quads and Triples contain a CS-Quad and a CS-Triple, and the remaining digit cannot be similar to the CS-Quad or CS-Triple.

CS-Repeating Doubles.
CS-Repeating Doubles there is a CS-Paired 4OAK M 44xx44xx M and 2 CSPairs M xx11xx22 M, the CS-Repeating Doubles #14, The CS-Paired 4OAstarts at position 1 and the second pair of the CS-4OAK starts at position 4.

Note: This page contains excerpts and basic information from the book "The Green Guide to Fancy Serial Numbers". Please consider adding a copy to your library, thank you.