The trust at issue was created by the decedent's mother. Under the terms of the trust, decedent was a co-trustee as well as a beneficiary. The trust authorized the trustees to pay any amount of the principal to the beneficiaries which the trustees deemed to be 'required for the continued comfort, support, maintenance or education' of the beneficiaries. Based on this language, the IRS found that the decedent had powers over the trust corpus, unrestrained by any ascertainable standard, which permitted him to invade it for his own benefit. In making this determination, they focused on the language relating to the 'comfort ' of the beneficiaries. The IRS, therefore, included the trust corpus in the decedent's gross estate.