Most of the Quenya declensions described in the Plotz letter are fairly well understood, but there is one that has long puzzled researchers. There is an unlabeled inflection using the suffix -s, appearing immediately below the locative inflection: caryas below ciryasse and lasses below lassesse (Plotz). In the same letter, Tolkien also placed the dative inflection (unlabeled) beneath the allative inflection: caryan below ciryanna and lassen below lassenna:

All.	ciryanna
	(ciryan)
Loc.	ciryasse
	(ciryas)

In the same document Tolkien gave the plural forms ciryais, lassis and the partitive plural ciryalis for this s-inflection. A similar “short locative” form appears in the Entu, Ensi, Enta Declension (EEED) probably from the late 1920s (VT36/8): [ent]os, [ent]es, [ent]as beside longer entosse, entesse, entasse. Until recently, this was nearly all the information we had about this case: that it was inflected by adding -s to vocalic nouns, and that it was (probably) etymologically related to the locative in a way similar to how the dative was related to the allative. Anthony Appleyard coined the term “respective” for this case based on one theory of its grammatical function:

The role of the case that I call ‘respective’ may relate to Locative as Dative relates to Allative: when a noun A is Allative, something goes to(wards) A, and when A is Dative, some object or action or favour ‘goes to’ A semi-literally or figuratively. Perhaps ‘-s’ means “concerning”, “with respect to”, “paying attention to”, and (most often) “about” in “think or talk or write about”, whence my name for it: when A is Locative the action is at A but does not move towards A, and when A is Respective the action concerns but does not directly affect or ‘go towards’ A (Quenya Grammar Reexamined, 1995).

There is no direct evidence supporting this theory of its use, however. Ales Bican also wrote about this declension at some length (the -s case, 2002). Ales pointed out that we do not know exactly what function the case serves, and following his lead I use the more neutral term “s-case” as a label for this inflection. As pointed out by Bican, not every instance of an s-inflection in the corpus has to correspond to the s-case decribed in the Plotz letter. Bican pointed out there are examples of s-inflections in the 1930s that seem to be a dative, and the existence of a 1930s s-dative was confirmed in later publications (PE21/61, Primitive Quendian Structure: Final Consonants, written in 1936, published in 2013).

In Bican’s article, he points out two phrases that might be examples of the s-case: the (untranslated) tengwar phrase calma hendas (the actual reading is qualma hendas but there is general agreement that the initial tengwa z is probably a mistaken a). Arden Smith theorized this phrase meant “a light in the eye” and was an example of the s-case, but without a gloss from Tolkien it is hard to know for sure. A more plausible example is the (deleted) phrase elli yas atintilar in a draft of the Namárië poem; this corresponds to the phrase yassen tintilar i eleni “wherein the stars tremble” in the finished poem. Thus the yas in the draft may serve a similar locative-like function as yassen.

Since Bican’s article was written, a few more pieces of evidence have been published. First, the existence of an ancient locative suffix -s has been confirmed: “The so called [Old Quenya] short allative, locative, allative end in n, s, l < nă, sĕ, lŏ, but were in restricted use” (PE21/69, Notes for Qenya Declensions, 1940s). The -n became the dative, the -l fell out of use (PE21/62) and the -s probably became the s-case.

Finally, a phrase from the 1940s has been published with examples and glosses that seem to fit a locative-like function for the s-case:

• qe e·kárie i kirya aldaryas, ni kauva kiryasta menelyas “if he finishes the boat by Monday, I shall be able to sail on Wednesday” (PE22/120-1, Quenya Verbal System, written in the 1940s, published in 2015).

Here aldaryas “by Monday” [sic., actually “by Tuesday”] and menelyas “on Wednesday” both seem to be examples of use of the s-case. This sentence was written two decades before the Plotz, but assuming these s-inflections serve the same grammatical function, they seem little different in use from the ordinary locative.

Neo-Quenya: Since we know so little about the s-case, and what little we know seems to indicate it was functionally similar to the locative, I would avoid using it in Neo-Quenya, and stick to the better understood locative suffix -sse instead. If you do want to use it, I would inflect it more or less like the dative, e.g. -es after consonantal nouns: atanes.

Some people use the term “short locative” for the s-case (including Tolkien in the quote from Notes for Qenya Declensions above), but I prefer to reserve that term for the reduced locative suffix -se.