refer to any member of a whole class or category of entities: these display purely semantico-referential meaning, and in the Peircean terminology are known as symbols. On the other hand, deixis is distinguished as a particular subclass of indexicality in general, which may be nonreferential or altogether nonlinguistic. In the older terminology of Otto Jespersen and Roman Jakobson, these forms were called shifters. Silverstein, by introducing the terminology of Peirce, was able to define them more specifically as referential indexicals. Non-referential indexicality Non-referential indices or "pure" indices do not contribute to the semantico-referential value of a speech event yet "signal some particular value of one or more contextual variables." Non-referential indices encode certain metapragmatic elements of a speech event's context through linguistic variations. The degree of variation in non-referential indices is considerable and serves to infuse the speech event with, at times, multiple levels of pragmatic "meaning." Of particular note are: sex/gender indices, deference indices (including the affinal taboo index), affect indices, as well as the phenomena of phonological hypercorrection and social identity indexicality. Examples of non-referential forms of indexicality include sex/gender, affect, deference, social class, and social identity indices. Many scholars, notably Silverstein, argue that occurrences of non-referential indexicality entail not only the context-dependent variability of the speech event, but also increasingly subtle forms of indexical meaning (first, second, and higher-orders) as well. Sex/gender indices One common system of non-referential indexicality is sex/gender indices. These indices index the gender or "female/male" social status of the interlocutor. There are a multitude of linguistic variants that act to index sex and gender such as: word-final or sentence-final particles:many languages employ the suffixation of word-final particles to index the gender of the speaker. These particles vary from phonological alterations such as the one explored by William Labov in his work on postvocalic /r/ employment in words that had no word final "r" (which is claimed, among other things, to index the "female" social sex status by virtue of the statistical fact that women tend to hypercorrect their speech more often than men); suffixation of single phonemes, such as /-s/ in Muskogean languages of the southeastern United States; or particle suffixation (such as the Japanese sentence-final use of -wa with rising intonation to indicate increasing affect and, via second-order indexicality, the gender of the speaker (in this case, female)) morphological and phonological mechanisms: such as in Yana, a language where one form of