A reaction status is assigned to each reaction during Rhea curation:

Status	Definition
Approved	All reaction participants are known and the reaction is chemically balanced for mass and charge.
Preliminary	There is experimental evidence for the reaction, but not all details are known, and therefore these reactions are usually unbalanced for mass or charge.
Obsolete	The reaction is no longer considered valid. These reactions are not searchable on the website, but the list of obsolete reactions is available on the Download page.