631.2—Definitions.
In addition to the definitions contained in sections 4, 301, and 303(e) of the Act and Part 626 of this chapter, the following definitions apply to programs under Title III of the Act and this part:
Substantial layoff (for participant eligibility) means any reduction-in-force which is not the result of a plant closing and which results in an employment loss at a single site of employment during any 30 day period for:
(a)
(1)
At least 33 percent of the employees (excluding employees regularly working less than 20 hours per week); and
Substantial layoff (for rapid response assistance) means any reduction-in-force which is not the result of a plant closing and which results in an employment loss at a single site of employment during any 30 day period for at least 50 employees (excluding employees regularly working less than 20 hours per week) ( section 314(b)(4) ).