18 CFR 1b.1 - Definitions.
For purposes of this part -
(a) Formal investigation means an investigation instituted by a Commission Order of Investigation.
(b) Preliminary Investigation means an inquiry conducted by the Commission or its staff, other than a formal investigation.
(c) Investigating officer means the individual(s) designated by the Commission in an Order of Investigation as Officer(s) of the Commission.
(d) Enforcement Hotline is a forum in which to address quickly and informally any matter within the Commission's jurisdiction concerning natural gas pipelines, oil pipelines, electric utilities and hydroelectric projects.