Which of the following is NOT a type of specification propane containers are manufactured under?

The selection of ISO as the answer reflects an important understanding of the standards and regulations governing the manufacture of propane containers. While ASME (American Society of Mechanical Engineers) sets codes for the design and construction of pressure vessels, and DOT (Department of Transportation, formerly known as ICC) establishes regulations for containers that transport hazardous materials including propane, ISO (International Organization for Standardization) is indeed a global organization that provides various standards but it does not specifically regulate the manufacturing of propane containers in the same way that ASME and DOT do.

The FAA (Federal Aviation Administration) primarily oversees aviation safety and would not be involved in regulating propane container specifications; however, its mention here highlights the specificity needed when identifying entities that govern propane container manufacturing standards. Thus, ISO stands out as not being directly relevant to the manufacture of propane containers.