Depending on the field of literature being surveyed, one might encounter the same compound referred to with different chemical formulas. An example of the most common difference is XYZ versus XYZ, where the labels of the two transition metals X and Y in the compound are swapped. The traditional convention XYZ  arises from the interpretation of Heuslers as intermetallics and is used predominantly in literature studying magnetic applications of Heuslers compounds. The XYZ convention on the other hand is used mostly in thermoelectric materials and transparent conducting applications  literature where semiconducting Heuslers (most half-Heuslers are semiconductors) are used. This convention, in which the left-most element on the periodic table comes first, uses the Zintl interpretation of semiconducting compounds where the chemical formula XYZ is written in order of increasing electronegativity. In well-known compounds such as FeVAl which were historically thought of as metallic (semi-metallic) but were more recently shown to be small-gap semiconductors one might find both styles being used. In the present article semiconducting compounds might sometimes be mentioned in the XYZ style.