As I think we are the main users of the UK tables in liblouis I thought I'd let you know that we very, very rarely have any Maths in our transcriptions, so I have no worry about any changes being made. I am no expert on table design and we have had to make changes to the character definitions in grade 1 to get what we want and maybe we haven't made the right approach! As we also have our embossers setup for US computer braille it could be that the original tables were setup for UK computer braille and this is were we are both getting the issues. I do know that the literary tables were at the time based on the US tables as there is evidence of some of the invalid US code being rem'd out.
HTH Paul On 13/10/2014 07:54, James Teh wrote:
Hi all,I am extremely confused by the way some of UK Maths has been implemented in liblouis*. I'd greatly appreciate it if someone could help clarify. Ultimately, I want Unicode braille output. This seems to be extremely difficult for UK Maths because of the way it's implemented.Let's take a simple fraction which I'll present in LaTeX for brevity: \frac{a+b}{c}As I understand it, in UK Maths, the braille should be (using US computer braille encoding):<a ;6b>_/cIn ukmaths_edit.ctb, \x0003 (which is defined as the start indicator for a fraction in ukmaths.sem) is defined as dots 5 6. Similarly, \x0004 (the end indicator for a fraction) is defined as dots 4 5. As I understand it, they should be dots 1 2 6 and 3 4 5, respectively.From what I can see, this has been done because ukmaths_single_cell_defs.cti defines "<" as dots 5 6 and ">" as dots 4 5. The practical upshot is that if you use us-table.dis as the first table in mathExprTable for ukmaths.cfg, this does give you valid US computer braille output. However, as far as I can see, it's impossible to get valid Unicode braille output.To make things more confusing, ukmaths_single_cell_defs.cti defines digits as upper digits with dot 6, so dots 1 2 6 is actually the digit "2" unless defined earlier (e.g. by us-table.dis).Why is it implemented this way? Shouldn't how the output is encoded be determined last, rather than the tables hacking around to get a specific output encoding? That is, the dots in the tables should all be correct so that any output encoding can be used, whether it be US computer braille, Unicode braille or something else. So, \x0003 should be dots 1 2 6 and \x0004 should be dots 3 4 5.Does anyone actually use these tables currently? Would such a change break things and why?Thanks, Jamie
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