The sources you cite try to draw the line between apposition and (pre)modification. It is nonsense. Apposition (as a grammatical construction) may stand in pre-position (premodifying the antecedent) and post-position (post-modifying the antecedent). But it doesn't change its NATURE.
The classification that your sources offer reminds me the classification of animals in one old Chinese "encyclopaedia". According to it all animals are divided into embalmed ones, suckling piglets and those that belong to the emperor.
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