I may not have spelled it right, however I need to know when an employer gives money for an employee to go out of town. Is it mandated by the IRS for that employee to spend the money on food only...
Or can it be used for personal purposes?

Someone please answer.
When a company sends an employee out of town and gives them money (Predium)
What purchases are allowed of the IRS?

Per Diem payments are for food, lodging and other expenses related to the employee's being away from home while working. The amount is set by the GSA (Government Accounting Office) for the location you are being sent to.

Make good choices on what you spend the money for. The IRS only comes into the picture if you spend more than the Per Diem amount to live away from home. If you spend more then you need to have receipts and can deduct only a percentage of the amounts in excess of the per diem paid. For tax information, check with your tax person.

What is your company rules that is what applies.

Some companies will only pay you for the exact expense, you save the receipt and they pay you back

If your company gives you, say 100 dollars a day that is just your money if you spend less it is your money