Answer from Kyle DeJute, Chair of the NBA Mathematics Braille Committee
Good day, Susan.
Thank you for your questions.
In response to your first question: Please do not use the UEB symbol for visible space (dots 346), because it comes from the UEB Guidelines for Technical Material, which should be avoided when creating a UEB-with-Nemeth transcription. Instead, I would suggest using the skeleton table format (Braille Formats, 2011 section 11.9.1.d), substituting the UEB low line (dots 46, 36) for the EBAE dash to indicate blanks to be filled. Use the same layout for the skeleton "hundreds-tens-ones" table that you use for the first, fully filled one.
In response to your second question: Within begin/end Nemeth indicators, you should use the double dash (36, 36, 36, 36) according to the Nemeth code book. UEB symbols are not used within Nemeth indicators, and Nemeth symbols are not used outside the confines of begin/end Nemeth indicators. So, for your equations later on in the book, I would use the following:
[braille]_% #56+100 .k ---- _:
Thank you again for your astute and well thought out questions.