There was a suggestion recently regarding a symbol that looks like a triangle pointing to the left -- that we follow rule XVI section 107. "Signs of shape which do not appear in the list of Basic Shapes must be represented by the use of one or more letters suggestive of the name of the shape being represented." Hopefully you haven't progressed too far with my earlier recommendation. It would be more efficient to use [braille]$bn for "bun", don't you think? And we would be adhering to the Nemeth Code. Or if your book is using different terminology, choose two letters to represent the name the authors have given the symbol.