superscription (n.)

1580s, "address or direction on a letter," from French superscript, from Latin superscriptus "written above," past participle of superscribere "write over or above something (as a correction)," from super "above" (see super-) + scribere "to write" (from PIE root *skribh- "to cut"). Meaning "number or letter written above something" first recorded 1901.