SUUNTO EON STEEL - Manual (Page 42)

WARNING: When diving with multiple gases, remember that the
ascent time is always calculated with the assumption that you use
all the gases found in the Gas(es) menu. Always check that you have
only the gases for your current planned dive defined before you
dive. Remove the gases that are not available for the dive.
3.17 Oxygen calculations
During a dive, Suunto EON Steel calculates partial pressure of
oxygen (pO2), central nervous system toxicity (CNS%) and
pulmonary oxygen toxicity, tracked by OTU (oxygen toxicity units).
The oxygen calculations are based on currently accepted exposure
time limit tables and principles.
By default in Air/Nitrox dive mode, CNS% and OTU values are not
displayed until they reach 80% of their recommended limits. When
either value reaches 80%, EON Steel notifies you and the value stays
in the view. In default Trimix mode, CNS% and OTU values are
displayed in the bottom-right corner field as scrollable info.
NOTE: You can customize views to always show CNS% and OTU.
3.18 Personal and altitude adjustments
There are several factors that can affect your susceptibility to DCS.
Such factors vary between divers, as well as from one day to
another.
42