However, to say that "RARS" stands directly for that string of words, or can be interchanged with it in syntax (in the same way that "CHF" can be usefully interchanged with "congestive heart failure"), is a prescriptive misapprehension rather than a linguistically accurate description; the true nature of such a term is closer to anacronymic than to being interchangeable like simpler acronyms are. The latter are fully reducible in an attempt to "spell everything out and avoid all abbreviations", but the former are irreducible in that respect; they can be annotated with parenthetical explanations, but they cannot be eliminated from speech or writing in any useful or practical way. Just as the words "laser" and "radar" function as words in syntax and cognition without a need to focus on their acronymic origins, terms such as "RARS" and "CHA2DS2–VASc score" are irreducible in natural language; if they are purged, the form of language that is left may conform to some imposed rule, but it cannot be described as remaining natural. Similarly, protein and gene nomenclature, which uses symbols extensively, includes such terms as the name of the NACHT protein domain, which reflects the symbols of some proteins that contain the domain – NAIP (NLR family apoptosis inhibitor protein), C2TA (major histocompatibility complex class II transcription activator), HET-E (incompatibility locus protein from "Podospora anserine"), and TP1 (telomerase-associated protein) – but is not syntactically reducible to them. The name is thus itself more symbol than acronym, and its expansion cannot replace it while preserving its function in natural syntax as a name within a clause clearly parsable by human readers or listeners.