What is the correct expression for a time indicating a specific hour in military time?

The correct expression for indicating a specific hour in military time is referred to as the 24-hour format. This system is utilized primarily in military contexts and many other international applications to avoid confusion that can arise from the use of the 12-hour clock system, which includes AM and PM designations. In the 24-hour format, the day runs from 0000 to 2359 hours, meaning that midnight is represented as 0000 and the last minute of the day is represented as 2359. For example, 1 PM is represented as 1300, which helps to clearly communicate times without ambiguity.

The other formats mentioned do not specifically relate to military time. The 12-hour format often causes confusion due to the use of AM and PM within the same day. The term "international format" may refer to various timekeeping conventions used in different parts of the world but is not recognized as a standard single format like military time. Decimal format typically pertains to expressing time in tenths or hundredths of an hour rather than through distinct hourly divisions, which does not correlate with how military time is structured.