found: Work cat.: Roy, M. Sign after the X, c2001:p. 13-14 (Its use as a first letter is limited to words of Greek origin mostly, or to those of African, Chinese, Vietnamese, or North/Central/South American native origin. ... X is ubiquitous in Latin ... The letter as an isolated grapheme has always been used in scientific and philosophical discourses to stand in for an unknown ... Twentiety-century semiotics states that the sign, even the grapheme, has an arbitrary relationship to meaning, representation, or sound; it is based on convention ... X has appeared on cave walls as one of the first symbols of language/representation/symbolism ... The discourse of otherness (xeno), youth culture (Generation X), UFOS (x-files), commix (X-men), sexuality, genetics, and cyberculture)