Thus a franchise tax may be measured by such proportion of the company's net income as its capital invested in the taxing State and its business carried on there bear to its total capital and business;[679] also by the net income justly attributable to business done within the State although a part of this was derived from foreign or interstate commerce;[680] also by such proportion of the company's outstanding capital stock, surplus and undivided profits, plus its long-term obligations, as the gross receipts of its local business bear to its total gross receipts from its entire business;[681] also by such proportion of the company's total capital stock as the value of its property in the taxing State and of the business done there bears to the total value of its property and of its business.[682] On the other hand, a "franchise" tax on the unapportioned gross receipts of railroad companies engaged in interstate commerce, was, as we saw above, held void;[683] as was also one which was measured by assigning to the company's property in the State the same proportion of the total value of its stocks and bonds as its mileage in the State bore to its total mileage, no account being taken of the greater cost of construction of the company's lines in other States or of its valuable terminals elsewhere.[684] Other examples were given earlier.[685] GROSS RECEIPTS TAXES, CLASSES OF The late Justice Rutledge classified gross receipts taxes which have been sustained by the Court as follows: (a) those which were judged to be fairly apportioned;[686] (b) those which were justified on a "local incidence" theory, or the burden of which on interstate commerce was held to be "remote";[687] (c) those which were justified as not inviting the danger of multiple taxation of interstate commerce.[688] Gross receipts taxes which, on the other hand, have been invalidated under the commerce clause he placed in the following groups: (a) those which were held not to be fairly apportioned;[689] (b) those which were not apportioned at all and were bound to subject interstate commerce to the risk of multiple taxation;[690] (c) those in which a discriminatory element was detected in that they were directed exclusively at transportation or communication;[691] (d) those in which there was no discrimination but a possible multiple burden;[692] and, of course, any tax which it disallows the Court is always free to stigmatize as an unconstitutional attempt to tax or license the interstate commerce privilege.[693] "MULTIPLE TAXATION" TEST