[tex4ht] tex4ht gives amsmath Error: \tag not allowed here

[Nasser M. Abbasi]

On 9/7/2018 3:29 AM, Michal Hoftich wrote:
> Hi Nasser,
> 
>> Ok, using equation instead of \[ \] does not produce error with tex4ht
> 
> Isn't \tag supposed to be used only with amsmath environments? I think
> you really shouldn't use it with \[ \]
> 
> Best regards,
> Michal
> 

You must be right. But the question is: Why then lualatex and pdflatex
do not generate an error or even a warning for the same input?

I've always went by the rule of  thumb: if it works correctly in
pdflatex, (i.e. no error), then it must be valid latex. This
is the first time where I see roles reversed: tex4ht detects
invalid latex while pdflatex does not.

--Nasser