In historical linguistics, a macrofamily, also called a superfamily or phylum, is a proposed genetic relationship grouping together language families (also isolates) in a larger scale classification. However, Campbell regards this term as superfluous, preferring "language family" for those classifications for which there is consensus and "distant genetic relationship" for those for which there is no, or not yet, consensus, whether due to lack of documentation or scholarship of the constituent languages, or to an estimated time depth thought by many linguists to be too great for reconstruction.