Representative assessee taxation: unallocated trust income taxed as association income or at the maximum marginal rate. Where income payable to representative assessees is not specifically receivable for identifiable beneficiaries or individual shares are indeterminate, tax is charged as if the income were the total income of an association of persons or, in specified exceptions, at the maximum marginal rate. For income wholly for charitable or religious purposes only the non-exempt portion is treated as income of an association of persons, and for partly charitable trusts tax is the aggregate of tax on the charitable portion (as if association income) and tax on the unallocated non-charitable portion at the maximum marginal rate. An explanation deems shares indeterminate unless expressly stated and ascertainable in the governing instrument.