hyphenation - Is "UTF-8-encoded" an overuse of hypens? Does "UTF-8 encoded" require a hyphen?

After reading usage of the phrase "UTF-8 encoded" ("UTF-8-encoded) at, for example, stackoverflow.com, in Howto identify UTF-8 encoded strings, and in an excerpt

...every character can be UTF-8 encoded.

from this answer, I began to question whether writing "UTF-8-encoded" is an overuse of hyphens, but a quick read over

Confusion over the general rules governing the use of the hyphen in English

When should compound words be written as one word, with hyphens, or with spaces?

indicates to me that "UTF-8-encoded" is correct usage of hyphens.

Is "UTF-8 encoded", though, correct and not require an additional hyphen? If it it is correct, why isn't the hyphen necessary?

Answer

I think it's something of a matter of personal style, or if writing for publication, the style guide of the intended publication. The name of the coding method is "UTF-8" (cf. http://en.wikipedia.org/wiki/UTF-8), so the hyphen between the character "F" and the character "8" is a part of the name. But looking at the first link you provide, the hyphen is not required from case 1 because the two parts, "UTF-8" and "encoded" do not have a combined meaning that differs to any significant degree from the phrase "encoded with UTF-8". It's also not required from case 2, because as pronounced, "8" ends in a consonant, and "encoded" begins with a vowel.

On the other hand, according to your link to question 889, one could argue that there should be a hyphen, but according to that site, only in the exceptional case that the phrase precedes the noun it modifies, as in "UTF-8-encoded document". But it's not clear to me that this exception applies in the absence of the following noun, for example in the construct "The document is UTF-8 encoded." And since this last statement is functionally equivalent to "The document is encoded in UTF-8.", I don't think that the hyphen is necessary. But I don't think a hard and fast rule applies here, and I can conceive of cases where I might see the construct with a hyphen between the "f" and the "8", and between the "8" and the following word might be useful.