He received a per diem allowance to cover his travel expenses.

他收到一笔按日计算的差旅费用补贴。

《柯林斯英汉双解大词典》

During authorized business travel and work assignments, the company provides the required transportation and services and pays a per diem allowance to cover reasonable living expenses.

在核准的商务出差和工作安排期间，该企业提供所需的运输和服务，并支付每日津贴以负担合理的生活开支。

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License agreements typically have a 10-year term, and require the licensee to pay the owner of the technology some combination of an upfront fee, royalty payments based on sales, and per diem and travel expenses of the engineers who help transfer the know-how and technology.

FORBES: Staking Out Your Market Position In China: Part I

Members of the Commission shall serve without compensation but shall be allowed travel expenses, including per diem in lieu of subsistence, as authorized by law for persons serving intermittently in the Government service (5 U.S.C. 5701-5707).

WHITEHOUSE: The White House