Whereas the earlier WORLD2 model lumped all capital investment into a single state variable from which it then split off the percentage of capital invested in the agricultural sector as a second state variable (a funny choice for a state variable, since percentages don't accumulate), the more modern WORLD3 model differentiates between capital invested in industry, capital invested in the service sector, capital invested in agriculture, and other capital investment.
The industrial capital is measured in U.S. dollars.