A response from a friend may help a little. It is described to me by a friend to be a universal dictionary symbol meaning that nothing more can be done to word as far as antonyms etc. (endings included).
I am not familiar with such a universal dictionary symbol. Have you tried looking in the front (or back) of this dictionary? There might be a listings of symbols it uses. If anything, this looks like a macron. If you can't find such a symbol listing in your dictionary, please let me know and I'll ask other foreign language experts. And if you find out more about this universal dictionary symbol, please share! I'd love to learn about it.
No luck. With the help of a librarian, I looked through two Spanish and one English dictionary. We were unable to find the symbol, or anything like the symbol.
I re-reviewed the rest of the print book and did not find the symbol used anywhere else and there is no other reference to it in the print text. (Note: there are no diacritics in this print book, so it probably isn't a macron.)
Whatever the symbol is... I think it would be of limited benefit to the reader since it does not appear anywhere else in this text, no questions are asked about it, and it is not needed for the reader to answer the questions. So, I think that I should omit it. What do I need to do to indicate the omission?
You have certainly researched this thoroughly. I can't think of anything else you could have done. I think this is now a situation calling for transcriber judgment. I think some transcribers would simply omit this unkown symbol that has no print reference and I would support such a decision. On the other hand, I know there are also transcribers who would write a TN. Since you have gone to the trouble of determining that this unknown symbol appears only once, I would consider a [u]brief [/u]TN preceding that entry that says the unknown symbol after the following entry word is omitted in braille. Your choice!