In Bhikkhu Bodhi’s Wisdom Publications version of MN there are small numbers for his footnotes, but also numbers in square brackets. I was curious what the numbers in square brackets meant?
Here’s a picture with both the square brackets and a footnote:
They refer to the Pali Text Society page number (an old reference system for suttas). If I’m correct, you’re reading MN 118, so in this case “[84]” refers to PTS mn.iii.84; the third volume of the PTS edition of the Majjhima, page 84.