Word for a moment in time defined with beginning and end

Solution 1:

I designed many databases containing this sort of information, but I don't think I ever had a persistent entity containing both Start and End Time (it was invariably StartTime + Span), so I never really needed a word for OP's pair of values or the period it represented.

It's usually associated with relatively short timespans (a word which OP might prefer), but the computer industry does actually have a commonly used term...

time slice/timeslice
A time interval during which a time-sharing system is processing one particular computer program. Also known as time quantum.

Solution 2:

The word "Interval" is the recommended term per ISO 8601, although in colloquial usage it has a connotation of being periodic.

Solution 3:

You can simply use the word period.

Solution 4:

Window, as in "window of time."

Solution 5:

You could consider duration

the length of time that something lasts or continues

Note that this is perhaps more frequently used to indicate the length of time rather than the start and stop point.

You also could use allocation. Allocate is defined as

1. to apportion for a specific purpose or to particular persons or things : distribute

2. to set apart or earmark : designate

Allocation could be used alone or as part of the term time allocation.