there isn’t, but been mentioned in interviews etc. And as that is common practice with other visas, its highly likely to be the same with DTV, although not yet confirmed or denied.
We will know soon though, as we are very close to DTV being 6 months since launch
its 180 total days spent. Doesn’t matter if you leave and come back. If you spend more than 180 days in thailand within the same calendar year (jan-dec) you are considered tax resident regardless of type of visa.