[luatex] How to get a \mid binary relation that grows in LuaTeX

[David Carlisle]

On 15 November 2017 at 16:04, Hans Hagen <pragma at wxs.nl> wrote:
> On 11/15/2017 3:53 PM, David Carlisle wrote:
>>
>> On 15 November 2017 at 14:16, Hans Hagen <pragma at wxs.nl> wrote:
>>
>> Hans, thanks for the reply
>>
>>> (3) the good news is that you can do this:
>>>
>>>      \left( a \Umiddle class 5 | b \right)
>>>
>>> Hans
>>>
>>
>>
>> Ooh that is news:-) (the luatex manual doesn't seem to mention a
>> possibility of class here)
>
>
> it's sort of an experiment ... which will probably stay ... so it can be
> revealed ...
>
>> but why 5 (closing)? I'd have expected to specify 3 (relation) to get
>
>
> these are internal classes which have more granularity
>
>  0   ord
>  1   op normal
>  2   op limits
>  3   op no limits
>  4   bin
>  5   rel
>  6   open
>  7   close
>  8   punct
>  9   inner
>  10  under
>  11  over
>  12  vcenter
>
>> symmetric spacing but that gives thinmuspace not thickmuspace (at
>> least with luatex 1.04 as distributed with texlive)
>
> Hans
>
>

Ah.  The extra granularity looks useful thanks, the numbering scheme
looks like it's going to be confusing though
it's not really an "internal class" if you can specify it as "class"
in the document, and then the numbering is different to \mathchar, or
even \Umathchar
I don't suppose it would be possible to put all the extended classes
above 8 and keep the old numbers for the old classes?

David