40 CFR § 90.102 - Definitions.
The definitions in subpart A of part 90 apply to this subpart. All terms not defined herein or in subpart A have the meaning given them in the Act. The following definitions also apply to this subpart.
Attitudinal control means the operator regulates either the horizontal or vertical position of the equipment, or both.
Support means that the operator holds the equipment in position so as to prevent it from falling, slipping or sinking. It is not necessary for the entire weight of the equipment to be borne by the operator.