Possible Clues:

• Twice checking 1 Down ought to be in the same place
• [Same source as before]
• "Ditto," in a footnote
• The same, in a footnote: Abbr
• In the same place (Latin; abbr)
• In the same place (used when citing a reference)
• The author wants to get a lot in the same chapter!
• Footnoter's 'ditto,' briefly
• Editor's shorthand for 'from the same source'
• In the same place (abbr)