From Tolkien Gateway

The Tehtar (Q, pron. [ˈteçtar]; singular Tehta) were a series of signs and symbols used when writing with the Tengwar, consisting of a variety of dots, curls and other marks written above or below Elvish letters. Most commonly, they were used to represent vowel-sounds, since Fëanorian script as it was commonly used did not provide characters to represent vowels. However, some of the tehtar were used to abbreviate writing, such as a bar above a consonant that added a preceding nasal of the same téma, or a bar below that indicated consonantal doubling, or a downward hook added to the bow that meant a following 's' (especially favoured in Quenya).[1]


  1. J.R.R. Tolkien, The Lord of the Rings, Appendix E, "Writing", "The Fëanorian Letters"