The Superessive case reference article from the English Wikipedia on 24-Apr-2004
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Superessive case

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Cases
Abessive case
Ablative case
Absolutive case
Accusative case
Adessive case
Allative case
Comitative case
Dative case
Dedative case
Elative case
Ergative case
Essive case
Genitive case
Illative case
Inessive case
Instrumental case
Locative case
Nominative case
Oblique case
Partitive case
Possessive case
Postpositional case
Prepositional case
Prolative case
Terminative case
Translative case
Vocative case
Declension
List of cases

The Superessive case is a grammatical declension indicating location on top of something. (Its name comes from Latin supersum, superesse: to be over and above.)

While most languages communicate this concept through the use of prepositions, there are some (most notably the family of Finno-Ugric_languages which includes Finnish and Hungarian) which make use of cases for this grammatical structure.

An example in Hungarian: a könyveken means “on the books”, literally “the books (on)”