Here, we present design considerations for CAF and contrast them with the approaches found in common featurizers. Composition featurizers utilize element symbols to index corresponding properties and perform arithmetic operations such as addition, subtraction, multiplication, division, and other on these properties. Commonly, features are calculated based on the stoichiometric ratio (or percentage) of elements and weighting the property according to the element content. For example, this approach could be used for regression type property prediction, where the property is assumed to scale with a gradual change in composition. However, the weighted approach might not be ideal for classification in cases where a certain subclass of compounds is studied with nearly identical ratios of elements (i.e., 1 : 1 vs. 49 : 51). Index ratios can indirectly relate to more structural information, often associated with distortions and symmetry reductions or simple atomic mixing (e.g., site defects). Atomic mixing in a compound could sometimes be detected from the composition. For instance, indices in chemical formulas with decimal points that summing up to unity often indicate atomic mixing, although only in-depth analysis of the crystallographic information can provide a definite answer. This observation was used to collect atomic mixing statistics in automated single crystal structure refinement approach. In databases, chemical formulas often are ordered in alphabetical order, however, the order of elements in chemical formula has a significant meaning. Positions of the elements indicate their electronegativity property, as elements are typically listed from electropositive to electronegative. For example, the radius ratio of elements rA/rB in an AB compound indicates the radius ratio of the cation over the anion. While electronegativity-based sorting approach works well for most compounds, discrepancies arise in some regions of the periodic table, for example, where certain transition metals are more electronegative than some nonmetals. Furthermore, various electronegativity scales might complicate the approach. An alternative is sorting based on Mendeleev numbers, which preserves the order of the elements in the periodic table, with each element having a unique value. However, no ideal sorting criterion exists given that the Mendeleev number method fails with a less diverse set of elements in a compound, such as predominantly nonmetal organics and same-group p-block element compounds.