In human history to date, only a few species of large animal have been domesticated. In approximate order of their earliest domestication these are: dog, sheep, goat, pig, ox, yak, reindeer, water buffalo, horse, donkey, llama, alpaca, Bactrian camel and Arabian camel.
For instance at sea level and standard weather (29.9 Hg) a gauge vacuum of -25.9 Hg is equivalent to an absolute pressure of 4 Hg. In other words, the vacuum gauges that read, for example, -25.9 Hg at full vacuum is actually reporting 4 Hg, or 136 mbar. That is still in the low vacuum range.
That set absolute pressure is usually 100 kPa. This is commonly referred to as gauge pressure. Boost pressure is relative to absolute pressure - as one increases or decreases, so does the other. It is a one-to-one relationship with an offset of -100 kPa for boost pressure. Thus a MaP sensor will always read 100 kPa more than a boost sensor measuring the same conditions.