Every proposition which says something indefinable about a thing is a subject-predicate proposition; every proposition which says something indefinable about two things expresses a dual relation between these things, & so on. Thus every proposition which contains only one name & one indefinable form is a subject-predicate proposition, & so on. An indefinable simple sign || symbol can only be a name, & therefore we can know, by the symbol of an atomic proposition, whether it is a subject-predicate proposition.