The first atom in a csexp list, by convention roughly corresponds to an XML element type name in identifying the "type" of the list. However, in csexp this can be any atom in any encoding (e.g., a JPEG, a Unicode string, a WAV file, …), while XML element names are identifiers, constrained to certain characters, like programming-language identifiers. csexp's method is obviously more general; on the other hand, Identifying what encoding such an item is in, and thus how to interpret it, is determined only by a particular user's conventions, meaning that a csexp application must build such conventions for itself, in code, documentation, and so forth.