The status of panlectal and polylectal grammars has been subject to debate amongst generative phonologists since the 1970s; one of the foremost areas of contention in regards to diaphonemes and diasystems is whether they reflect the actual linguistic competence of speakers. William Labov, although warm to the construction of a panlectal grammar, argued that it should be based in speakers' linguistic competence. Peter Trudgill argues against the formation of diasystems that are not cognitively real and implies that polylectal grammars that are not part of native speakers' competence are illegitimate. Similarly, cautions that polylectal grammars are only appropriate when they "result in claims about speaker-hearer's capabilities..."