Shorthand systems can be classified according to their place on the orthographic versus phonetic spectrum.
purely orthographic system mirrors the spelling of its native language.
An orthographic shorthand for English might start out with just 26
symbols to represent the letters A to Z and then add a few symbols to
stand for the most common words.
A purely phonetic
system writes a language based on its pronunciation with no regard for
how it is spelled. In a phonetic system for English, the shorthand
outlines for off, cough and staph would all end with same symbol which represents the F sound.
systems use a mixed approach. In Gregg Shorthand, for example, the
consonant sounds are written phonetically (in general). Some of the
vowels are lumped together in a way that is inspired by their most
common spellings in English: the /eɪ/ diphthong of play, the /æ/ vowel in cat, the /ɑ/ of calm and the /ə/ of tuna are all written with the large circle called “a.” These phonemes have nothing in common except that they are normally written with the letter A in English.
claims made by promoters of various shorthand systems often do not
match their reality. Many stenographic scripts that claim to be purely
phonetic are partly orthographic and vice versa.