production period
(5) Definitions For purposes of this subsection— (A) Long useful life Property has a long useful life if such property is— (i) real property, or (ii) property with a class life of 20 years or more (as determined under section 168 ). (B) Production period The term “production period” means, when used with respect to any property, the period— (i) beginning on the date on which production of the property begins, and (ii) except as provided in paragraph (4), ending on the date on which the property is ready to be placed in service or is ready to be held for sale. (C) Production expenditures The term “production expenditures” means the costs (whether or not incurred during the production period) required to be capitalized under subsection (a) with respect to the property.