The value of the company's physical, fixed assets once accumulated depreciation has been subtracted.

Gross Property Plant and Equipment (or PPE at cost) minus Accumulated Depreciation

This number is useful when analyzing how well a company generates sales revenue from its physical investments. The ratio used in this analysis is the fixed asset turnover ratio, equal to Net Sales / Net PPE. It is important to note that net PPE is not an "external" measure of value - it is simply that part of the cost of acquiring physical assets (PPE) that has not yet been expensed.