Asof

Asof, written as two words in ordinary English, is a prepositional phrase that signals the point in time at which a statement, record, or condition is considered to be true.

In general usage, as of is used to mark a snapshot in time. It implies that the described situation may change after the indicated moment and does not claim ongoing validity beyond it.

In data reporting and finance, as of a date denotes the exact time the figures apply. Reports may be labeled 'as of December 31, 2023' to indicate data validity as of that date, isolated from subsequent changes.

In computing, asof appears as a keyword or function in some time-series systems. For example in the q language used by kdb+, asof joins align two data sets on timestamps, selecting the most recent row with a time not after the other.

Because of its generic nature, the term's precise meaning depends on context, and care should be taken to define the reference date or time when reporting or analyzing data.