Most of us are probably aware that the original manuscripts and early copies of the books of the Bible did not have chapter and verse numbers. These were added centuries later for convenient reference. However, some might not be aware that there are actually many competing reference schemes for dividing the Bible into books, chapters and verses. Take this snapshot by way of example:
In the LXX (the Greek version of the Old Testament) Esther 5:1a is Esther 15:2-15:4 in the KJV. The use of letters here (as in 1a) indicates that this material is in the Greek, but not the Hebrew, edition of Esther, which added material the Latin translators moved to the end of the book. The English tradition of versification more closely follows the Latin in Esther, thus accounting for the radically different chapter number. But it gets more complicated than that: there are differences between the Latin numbering and the English, so Esther 15:2-15:4 in the KJV is Esther 15:5-15:7 in the Latin Vulgate. But after Vatican II there was a concerted effort to make the Vulgate follow the older Greek and Hebrew traditions more closely, so the Nova Vulgata, or New Vulgate, numbers that section as Esther 5:2a-5:2c. But to make matters worse, the LXX numbering we use today comes from the Stuttgart edition, but the numbering in the older Cambridge edition edited by Swete and several other, older editions follow a different LXX numbering. They designate Esther 5:1a as Esther D 2 – D 4, introducing the use of letters as chapter indicators for the Greek additions.