The definition of stationary source includes transportation containers used for storage not incident to transportation and transportation containers connected to equipment at a stationary source for loading or unloading (40 CFR Section 68.3). In a January 6, 1998 final rule (63 FR 640), EPA clarified that if a container remains attached to the motive power that delivered it to the site, even if a facility accepts delivery, it would be in transportation, and the contents would not be subject to threshold determination (63 FR 643).