Textual criticism
Although Greg argued that an editor should be free to use his judgment to choose between competing substantive readings, he suggested that an editor should defer to the copy-text when "the claims of two readings ... appear to be exactly balanced. ... In such a case, while there can be no logical reason for giving preference to the copy-text, in practice, if there is no reason for altering its reading, the obvious thing seems to be to let it stand." The "exactly balanced" variants are said to be indifferent.

Q: What do editors call variants that are exactly balanced?
indifferent