Usage of decisiontype values in table pwodecisionhistory

Hi all,
I would like to understand when and how each decisiontype value is used.
For example, I’ve seen that the value "query" is stored when someone raises an inquiry on a request.

Could you please explain (or point me to documentation about) the meaning and usage of all possible decisiontype values in pwodecisionhistory ?

Thanks in advance for any detail or reference.