There is a persistent illusion in our world that writing an EMS code is a technical task — something you learn once, apply mechanically, and never question again. In reality, it is one of the most misunderstood everyday tools we use. Not because the system is unclear, but because people consistently treat it as simpler than it actually is.
Writing an EMS code correctly requires three things at the same time: precise observation, strict adherence to the system, and the intellectual honesty to admit when something is not clear. Most errors do not come from a lack of knowledge of codes, but from skipping one of these steps. And once that happens, EMS stops being a reliable description and becomes an assumption — sometimes even a convenient one.
A significant number of EMS codes we encounter in pedigrees, catalogues, and even judge reports are not the result of careful evaluation. They are guessed, simplified, or copied. And the moment we accept “approximately correct” as good enough, the entire purpose of a standardized system begins to collapse.
This becomes even more important once we accept a simple but often ignored fact: EMS codes describe what we see – not what a cat truly is. And just like in judging, interpretation always plays a role in evaluation, which is exactly why understanding systems matters more than memorizing them.
This is Not Just a Label
An incorrect EMS code is not a harmless detail. It affects how breeders interpret inheritance, how cats are presented, and how future decisions are made. A wrong tabby pattern is not cosmetic — it creates false expectations. Incorrect white coding is not just untidy — it misrepresents the distribution of white. Misidentifying shaded, shell, or tabby categories does not stay on paper — it feeds directly into breeding logic.
This essay is also available as a short video lecture. The full written version continues below.
The idea that “experienced people know anyway” is exactly what allows bad EMS habits to survive for years without being challenged.
The Structure is Fixed — and it Matters
One of the most basic rules is also one of the most frequently ignored. EMS is not written freely, and it is not structured according to visual importance or verbal description. Numerical codes must be written in ascending numerical order — and that order reflects the structure of the system itself.
This means that the amount of white (01–09) always comes before tabby or tipping codes (11, 12, 21–25), which in turn come before pointed or related designations (31–33), and so on. This is not optional. It is how the system is defined.
A very typical real-life mistake illustrates this perfectly. A cat such as SIB ns 09 21 33 is often incorrectly written as SIB ns 21 33 09, simply because people think of the colour as “seal silver tabby point with white” and follow the wording instead of the system. Or they assume that white is somehow “less important” and can be pushed to the end.
It cannot.
Once you stop respecting the numerical order, you are no longer writing EMS correctly. You are rewriting the system to fit your thinking.
White is Defined — Not Estimated
White spotting is one of the areas where discipline breaks down most visibly. Codes 01, 02, 03 and 09 are not descriptive labels based on impression. They represent clearly defined categories of white distribution. Code 09, for example, is not “a bit of white” — it refers to cats with less than approximately 30% white.
And yet, in practice, white is often coded based on what “feels right” or what looks visually balanced, rather than what actually fits the category. Cats are moved between 03 and 09 casually, or assigned 02 because it looks more impressive, without proper evaluation.
This is not a minor inconsistency. It directly affects how the cat is interpreted — and how its offspring will be expected to look.
Code 21 is Not a Safety Net
Few EMS numbers are misunderstood as consistently as 21. It is often treated as a fallback — a convenient way to avoid making a decision when the pattern is unclear or poorly defined.
That is not what it is for.
Code 21 is used when the tabby pattern cannot be specified — but only in specific, restricted situations where the system requires it. It is not meant to compensate for weak markings, unclear contrast, or lack of confidence. If a cat clearly shows a defined pattern such as blotched, mackerel, spotted or ticked, then 22, 23, 24 or 25 must be used.
Using 21 in those cases is not cautious. It is incorrect.
And this is exactly where understanding the system matters more than memorizing it. There are situations where 21 is expected — and situations where it should not appear at all. Confusing the two is one of the most reliable signs that EMS is being applied mechanically rather than understood.
Exceptions make this even more obvious. Snow bengals, for example, are pointed cats — but they are still coded with defined patterns such as spotted (24) or marbled (22), combined with pointed designations. Writing them automatically with 21 simply because they are pointed is a textbook example of applying a rule without understanding it.
Eye Colour is Not Optional Where it Matters
Another area where shortcuts are common is eye colour coding. In certain categories, eye colour is not an additional detail — it is an integral part of the EMS description.
White cats must have their eye colour specified. High-white categories such as van (01) and harlequin (02) also require eye colour to be explicitly indicated. This is not a decorative addition; it is part of how those cats are classified and even judged in practice.
Ignoring this, or assuming that eye colour is “obvious”, is simply incomplete coding.
At the same time, there are situations where eye colour should not be redundantly written because it is fixed by breed characteristics. Understanding when it is required and when it is implied is part of using EMS correctly — and this is exactly where many people reveal whether they understand the system or just repeat patterns.
Breed Restrictions are Part of the System
EMS is not a universal template applied identically to every breed. It operates within the framework of breed-specific rules and restrictions, and ignoring those restrictions is one of the fastest ways to produce incorrect codes.
Some breeds are limited to specific colour categories, some to specific patterns, and some to specific pointed variants. In those cases, writing redundant or impossible combinations does not make the code more complete — it makes it wrong.
A simple example illustrates this clearly. In a breed restricted to pointed cats, writing the pointed code again is unnecessary. The restriction already defines it. Writing something like RAG n 21 33 instead of RAG n 21 does not add information. It shows that the system is being applied mechanically instead of logically.
Understanding EMS without understanding breed rules is not enough. In practice, the two cannot be separated.
The Most Dangerous Habit: Copying
Perhaps the most widespread and least discussed problem is the habit of copying EMS codes from existing pedigrees without re-evaluation. Once a code appears in an official document, it gains authority. From that moment on, it gets repeated — in catalogues, in databases, in future generations.
If the original code was wrong, the error becomes permanent.
This is how incorrect EMS descriptions propagate through entire lines, sometimes for years, without being questioned. Not because they are correct, but because no one takes responsibility for verifying them again.
Repetition is not validation.
Phenotype is Only the Starting Point
It is often said that EMS is based on phenotype, as if that settles the discussion. It does not. Phenotype is the starting point, but it must be interpreted within the rules of the system and within what is genetically possible.
If something is unclear, it requires further evaluation. If something contradicts known limitations, it requires reconsideration. Blindly trusting the first impression is not expertise — it is the absence of it.
The real skill is not in recognizing the obvious, but in knowing when the obvious is not enough.
The Real Problem is False Certainty
The most damaging EMS errors are rarely made by people who know nothing. They are made by people who know just enough to feel confident and not enough to question themselves. That is why the same mistakes repeat endlessly: wrong order, lazy use of 21, missing eye codes where they are required, redundant codes where they should be omitted, white coded by impression, patterns assigned by preference, pedigrees copied without thought.
None of this is caused by a flaw in the system.
It is caused by the way the system is used.
EMS is precise. It is structured. It works. But only if it is applied with discipline, consistency, and a willingness to think — not just to write.
Without that, it becomes exactly what many people already treat it as: a string of letters and numbers that looks convincing, but does not actually mean what it should.
With it, it becomes what it was always intended to be — a reliable language.
Written by Trpimir-Frane Sulić
President of Felis Croatia (KMFC)
WCF Judge
