Personalizing your dictionary
The dictionary's purpose
English steno uses dictionaries because it is very difficult to spell a word based on pronunciation. Trying to systematically encode all the English spelling rules and exceptions is difficult. It is much easier to use a file that directly maps steno outlines to English words. These mappings, of course, are not just decided arbitrarily. They do follow rules, but these are much easier for humans to understand than computers.
For languages with much more regular spelling, dictionaries aren't always necessary. It may be desirable to design what's called an orthographic system that is based entirely on spelling; chords on the steno layout are assigned to characters rather than sounds. With these, dictionaries may not even be necessary as the system only has to combine character groups together. Orthographic systems do exist for English, but they are generally slower than more traditional steno systems. This is mainly due to the less consistent spelling in the English language.
The rationale behind different dictionaries
English steno is built on the idea that no two stenographers' dictionaries are the same. For some, this may seem odd—why not just standardize steno and have everyone learn the same theory/dictionary?
Well first of all, English is a complicated language with different dialects and accents. With steno being primarily phonetic, it would difficult to create a single theory for all English speakers. More importantly, however, there are different ideas as to how the English language should be encoded on the the layout. Some steno theories are more heavy in rote memorization and require you to memorize more arbitrary steno strokes. Some steno theories rely more heavily on spelling instead of phonetics. Some steno theories like to split words more logically, while others may be more open-ended. There is no single "best" steno theory since some ideas are more intuitive than others depending on the person. Different theories click for different people.
Different dictionaries within the same theory
Even within one theory, different stenographers will have different dictionaries. This is due to the fact that a lot of steno theories are at least a little open-ended. It would be difficult to create a rule for every single edge case in the English language. Additionally, to expect everyone to follow these subtle rules would be unrealistic. Most hobbyists start off adding simple entries to their dictionaries.
For example, the steno stroke APD
does not represent any word in the English language. If you write about the Albuquerque Police Department often, this is a good stroke that you can use. On the other hand, you may find yourself accidentally stroking APD
instead of APT
when writing the word "apt"; this would be a good misstroke entry to add. It is also conceivable that the sound represented by this stroke is actually a word found in some particular niche circle. In this case, it may make sense to an individual part of this community to assign APD
to this niche term. What this stroke is assigned to depends entirely on the person, their writing style, and what they write about.