Surely "erratum", since you're only making one correction?
Well, not any more, is it? :)
Alternatively, perhaps "errata" has come to act as a mass noun when referring to corrections which are measured in effectively continuous units like paragraphs, rather than traditional lists? :)
Well, not any more, is it? :)
Alternatively, perhaps "errata" has come to act as a mass noun when referring to corrections which are measured in effectively continuous units like paragraphs, rather than traditional lists? :)