The phrase "a letter designating" is correct and usable in written English.
It can be used when referring to a letter that specifies or identifies something, such as a role, title, or designation.
Example: "Please send a letter designating the new responsibilities of each team member."
Alternatives: "a letter indicating" or "a letter specifying".
This is followed by a lowercase letter designating the order of publication, and a numerical designation indicating the number of diagnostic sites that differentiate it from the subfamily consensus.
A suffix letter designates variants of a basic aircraft, with the first model being "A" and subsequent series letters being assigned the next letters of the alphabet (skipping "I" and "O" to avoid confusion with the numbers "1" and "0").
†The letter designating the New York MLVA type follows PulseNet PFGE pattern designation.
A later review of 16 fatal fires, from the Blackwater fire in 1937 through 1956, led managers of the USFS to implement the Ten Standard Firefighting Orders in 1957, which were later changed to FIREORDERS in 1987, with each letter designating one of the ten orders.
Findings were contrasted over the different sites, which we have designated with the subscripts cap (for capitals) and hum (in sites where humanitarian services were implemented) after the first letter designating the countries in question (i.e., N, P, U).
The exceptions are France, where foals are given a name beginning with a letter of the alphabet designated to be used for that year; and Italy, where colts' names must begin with the letter or letters designating the stallion line, while fillies' names begin with the letter designated for a given year.
The third letter designates hot (h) and cold (k) in arid and hot summer (a), warm summer (b), cold summer (c) and very cold summer (d) in temperate and cold climates.
Abbreviations following the forest names are as follows: first letter designates the forest, second two letters indicate state.
The twenty-eighth and final letter designates "the levels, stations, and stages", that is, the invisible degrees of perfection achieved by the unfolding of human souls on the path of the Return.
Sure, it has the four extra letters designating it as a Facebook application, but it's hardly an eyesore.
