From where can I get the name of the AP invoice workflow initiator in EBS?

How can I get the name of my AP invoice approval workflow initiator?  Is it stored in a table somewhere?  If not, is there a way to capture the name of the logged in user who is initiating the invoice approval workflow?  I would like to capture this name (initiator/logged in user) using PL/SQL.  We are on EBS version 12.2.6.