What do the numbers in brackets in Heath's translation of Euclid mean?

Question

In Heath's translation of Euclid, the Common Notions appear as follows:

Common notions

1.Things which equal the same thing also equal one another.
2. If equals are added to equals, then the wholes are equal.
3.If equals are subtracted from equals, then the remainders are equal.
[7] 4. Things which coincide with one another equal one another.
[8] 5. The whole is greater than the part.  

What do the numbers 7 and 8 refer to? They are not footnotes, or references to notes, appendices or other material and I am unable to find any hints in the text itself. Are these in some way related to Stephanus' numbers in Plato or something?

This text is found on page 155 of Volume 1: https://ia802205.us.archive.org/14/items/euclid_heath_2nd_ed/1_euclid_heath_2nd_ed.pdf

Answer 1

The numbers in bracket refer to a numeration employed by some authors but changed by Heath because he rejected some common notions as spurious. See Heath's note on "Common Notions 2, 3" on page 223.

Answer 2

Pure speculation follows

Starting on page 224 of the linked text, there is a lengthy "Note on Common Notion 4." Immediately following this, on page 232, there's a very brief note called "Common Notion 5." Immediately following that, there's a note on "Other axioms introduced after Euclid's time." That note begins with a "[9]" notation.

So perhaps it is part of an index system within the book that just didn't end up being used, or something intended as a note to the publisher that got left in inadvertently.

Possibly going against this explanation is that there doesn't seem to be any sense in which these are the seventh and eighth notes, whether in the section or in the notes as a whole.