Most of the names of major characters in the poem have special meanings. These are briefly explained as follows:
Archimago > "Arch Mage", "Arch Magician"
Sometimes there is a qualifying parenthesis giving information on the etymology or adding comment:
Una > "One" (Latin; she is the sole Truth)
Character-names from the poem and from classical mythology are typically explained once only, on their first occurrence. If you encounter a name which is not defined, then it has appeared somewhere before. The list of proper nouns will quickly help you to find it.
THE TEXTUAL APPENDIX
A textual appendix, detailing actual or proposed departures from the copy-text, is incorporated. The Textual Appendix records:
(a) obvious misprints;
(b) lections from 1590 or 1609 which seem preferable;
(c) lections from 1590 or 1609 which throw light on the spelling,
punctuation or sense of 1596;