Are the former determiners in examples such as her book, and the latter personal pronouns, as in The book is hers?
This obviously raises the question: which is correct? Is her in her book a determiner or a pronoun? In our grammar videos (https://www.youtube.com/user/engliciousgrammar), especially videos 2 and 3, we hedge our bets and say that her belongs to both classes, i.e. it’s both a determiner and a pronoun, because this is what the NC seems to be claiming.
In my view it is best to regard her in her book, as well as hers in That book is hers, as possessive pronouns. Her in her book can then be said to have genitive case, and is analogous to Janet’s book.
However, in the Grammar, Punctuation and Spelling tests for KS1 and KS2, it is always assumed that these words are determiners, not pronouns, despite what it says in the glossary.
The National Curriculum Glossary has been integrated into the Englicious and can be viewed here: