Each type of vowel (A, E, I, O, and U) can function as a long vowel (L), a short vowel (S), a reduced vowel (R), or an unchangeably long vowel (UL). (Note: Some grammars transliterate each of the same-type vowels differently (e.g., “a” with a bar over it for Qamets, “a” with a circumflex over it for a Patach, and so on); since our goal is to read the Hebrew text - not to convert the Hebrew into English characters, I simplified the transliteration scheme accordingly.)
Long vowels can change to other, shorter sounds in a given word. For example, a Qamets can be shortened to a Patach when certain changes are made to the word’s morphology. Reduced vowels only appear under guttural letters and replace the function of the vocal sheva for those letters. Grammatically, chateph forms behave just like the sheva.
Hebrew Nikkudot (by class)
An alternate way of classifying the vowels is according to their class (Long, Short, Reduced, or Unchangeably Long). The following table summarizes the vowel classes: