I'm trying to define a QA context about especially cold ice-worlds(maybe they should be called cryo-worlds), where surface temperature range 0-100°K. I noticed there is not a tag for ice-world, nor cryo-world, and cryogenics tag description says it's reserved for cryogenic hibernation specifically. I did see the ice and dry-ice tags, although dry ice is only about 216.6 °K, and the context I was trying to get at was much colder than that. According to Wikipedia cryogenic gasses liquify at or below 123°K...
...and so I've used the cryogenics tag, I hope this is not too egregious a violation, although I was thinking I'd like to propose a couple new tags:
Quick freezing point chart
freezing points H2O 273.2 °K CO2 216.6 °K CH4 90.70 °K CO 68.13 °K N2 63.15 °K
I'd rather not used tags inappropriately if at all possible, but the large discrepancy in temperatures for each of these substances is so broad, and I think could help differentiate different types of cold worlds scenarios for science-based and hard-science Q&A.