Indian South African English Indian South African English (ISAE) is a sub-variety that developed among the descendants of Indian immigrants to South Africa. The Apartheid policy, in effect from 1948 to 1991, prevented Indian children from publicly interacting with people of English heritage. This separation caused an Indian variety to develop independently from white South African English, though with phonological and lexical features still fitting under the South African English umbrella. Indian South African English includes a "basilect", "mesolect", and "acrolect". These terms describe varieties of a given language on a spectrum of similarity to the colonial version of that language: the "acrolect" being the most similar. Today, basilect speakers are generally older non-native speakers with little education; acrolect speakers closely resemble colonial native English speakers, with a few phonetic/syntactic exceptions; and mesolect speakers fall somewhere in-between. In recent decades, the dialect has come much closer to the standard language through the model taught in schools. The result is a variety of English which mixes features of Indian, South African, Standard British, creole, and foreign language learning Englishes in a unique and fascinating way. ISAE resembles Indian English in some respects, possibly because the varieties contain speakers with shared mother tongues or because early English teachers were brought to South Africa from India, or both. Four prominent education-related lexical features shared by ISAE and Indian English are: tuition(s), which means "extra lessons outside school that one pays for"; further studies, which means "higher education"; alphabets, which means "the alphabet, letters of the alphabet"; and by-heart, which means "to learn off by heart"; these items show the influence of Indian English teachers in South Africa. Phonologically, ISAE also shares several similarities with Indian English, though certain common features are decreasing in the South African variety. For instance, consonant retroflexion in phonemes like /ḍ/ and strong aspiration in consonant production (common in North Indian English) are present in both varieties, but declining in ISAE. Syllable-timed rhythm, instead of stress-timed rhythm, is still a prominent feature in both varieties, especially in more colloquial sub-varieties. White South African English Several white South African English varieties have emerged, accompanied by varying levels of perceived social prestige. Roger Lass describes white South African English as a system of three sub-varieties spoken primarily by White South Africans, called "The Great Trichotomy" (a term first used to categorise Australian English varieties and subsequently applied to South African English).