• Produced capital and urban land—machinery, buildings, equipment, and residential and nonresidential urban land, measured at market prices.For brevity, the term produced capital is used in the book to include produced capital and urban land.
• Natural capital—energy (oil, gas, hard and soft coal) and minerals (10 categories), agricultural land (cropland and pastureland), forests (timber and some nontimber forest products), and terrestrial protected areas (for brevity, referred to simply as protected areas in the book). Marine-protected areas are not currently included. Natural capital is measured as the discounted sum of the value of the rents generated over the lifetime of the asset.