Say you are in the US. You are self-employed. During the year you have to travel to country X (say, Japan) for 20 days to see one of your clients. It is pure 100% business travel.
For travel within the US (if I'm not mistaken) you look up the standard Lodging amount per day, and standard M&IE amount per day, for the city in question. (Example from the GSA.) You are then (I think?) allowed to deduct one-half of both of those two amounts combined, per day.
So, regarding international travel.
So, you were in Japan for 20 days....
I believe you have to start on the State department web site to get the "standard" per diem: https://aoprals.state.gov/web920/per_diem_action.asp?MenuHide=1&PostCode=10273
(1) For the "20 days in Japan". In fact what do you claim as the accommodation expense? Is it 276/day? Is it one half of 276/day? Is it your actual hotel expenses? Or something else altogether?
(2) Then for M&IE. For the "20 days in Japan". Is your deduction the 227/day seen in that image? Or half of that? Or something else?