On phase diagram of water, solid to state border is a straight vertical line. Someone can argue it is only an approximation and nature cannot have vertical lines. For me however, it is clearly vertical. There exist no mention of this limit and it is not given a name. What is the name of this point, if such name exists, and what is the pressure value of it? If it is not measured, why? It seems like a very important point. Is there a measured, exact value of that point, not calculated or approximated?
In response to comments below (website does not reacts to my attempts to send a comment): I wrote 0.0 °C which is one-decimal digit. Anyone can see the line is absolutely straight in range that stretches at least from 10 mbar to approximately 10 bar which is a very big range. The upper limit of this range is not defined or named which is what my question is about.