The use of "Serbo-Croatian" as a linguistic label has been the subject of long-standing controversy. Wayles Browne calls it a "term of convenience" and notes the difference of opinion as to whether it comprises a single language or a cluster of languages. Ronelle Alexander refers to the national standards as three separate languages, but also notes that the reasons for this are complex and generally non-linguistic. She calls BCS (her term for Serbo-Croatian) a single language for communicative linguistic purposes, but three separate languages for symbolic non-linguistic purposes.