<P> In most of the alphabets of India and Southeast Asia, vowels are indicated through diacritics or modification of the shape of the consonant . These are called abugidas . Some abugidas, such as Ethiopic and Cree, are learned by children as syllabaries, and so are often called "syllabics". However, unlike true syllabaries, there is not an independent glyph for each syllable . </P> <P> Sometimes the term "alphabet" is restricted to systems with separate letters for consonants and vowels, such as the Latin alphabet, although abugidas and abjads may also be accepted as alphabets . Because of this use, Greek is often considered to be the first alphabet . </P> <P> A featural script notates the building blocks of the phonemes that make up a language . For instance, all sounds pronounced with the lips ("labial" sounds) may have some element in common . In the Latin alphabet, this is accidentally the case with the letters "b" and "p"; however, labial "m" is completely dissimilar, and the similar - looking "q" and "d" are not labial . In Korean hangul, however, all four labial consonants are based on the same basic element, but in practice, Korean is learned by children as an ordinary alphabet, and the featural elements tend to pass unnoticed . </P> <P> Another featural script is SignWriting, the most popular writing system for many sign languages, where the shapes and movements of the hands and face are represented iconically . Featural scripts are also common in fictional or invented systems, such as J.R.R. Tolkien's Tengwar . </P>

What system forms the basis for writing throughout east asia