A specialization of IDString. Each instance of this collection is a proper name considered as a character string. Instances of ProperNameString include city names (e.g. "Dallas"), person names (e.g. "Douglas" -- see HumanNameString), brand names (e.g. "Jello" -- see #$BrandName), company names (e.g. "Apple"), book titles, etc. Note that it is also possible to consider proper names not as character strings but as instances of LexicalWord -- for that, see Name and its specializations (and see nameSpelling to relate the two). (en)