What is the definition of "process"?

Process, as defined at 40 CFR §68.3, means any activity involving a regulated substance, including any use, storage, manufacturing, handling, or on-site movement of such substances, or combination of these activities. Any group of vessels that are interconnected, or separate vessels that are located such that a regulated substance could be involved in a potential release, is considered a single process. The owner or operator of the stationary source must make a reasonable determination as to whether two or more vessels may be involved in the same accident, or whether a release from one vessel may be anticipated to lead to a release from another. The owner/operator should document his decision as to whether the individual vessels do or do not constitute a single process.