ISO 639-6,代表言語號名的號碼 – 部份6: 原全涵蓋言語變款的Alpha-4號碼 (Codes for the representation of names of languages — Part 6: Alpha-4 code for comprehensive coverage of language variants),是ISO 639系列當中提議提議的國際標準,開發者是ISO/TC 37/SC 2 (International Organization for Standardization, Technical Committee 37, Subcommittee 2: Terminographical and lexicographical working methods)。本套標準用4字的號碼來表現言語佮言語家族的變款。