Hi Georgia. Thank you for posting your concerns about the updated Errata/Addenda to "An Introduction to Braille Mathematics," the lesson manual for learning the Nemeth Code.
YES, you should "undo" the old Errata. This does not necessarily mean that what was stated before is wrong, but may merely mean that it was an unnecessary or misleading comment. For example, many of the items noted in the old errata had to do with spacing issues in the print that--regardless of how they are printed--do not effect spacing rules in braille.
I appreciate your report regarding typos and will make those changes in the next release. An updated version will be available only after the new Braille Formats has been released and we have a chance to incorporate any effects this may have on the Nemeth Code.
Those who do not have a copy of the Errata/Addenda may request a copy from the NFB by contacting Jennifer Dunnam, Manager of Braille Programs, National Federation of the Blind Jernigan Institute, e-mail: firstname.lastname@example.org