Word for reoccurring time things like "monday" or "the 15th" or "9 o'clock"

Question

What "monday", "the 15th" and "9 o'clock" have in common is that they repeat over and over. Every week has a monday, every month has a 15th and every day has a 9 o'clock. Is there a word for such a phenomenon?

I'm a programmer trying to document a feature of the syntax used to enter these types of things. A specific word would be really useful as I keep having to explain the concept every time I mention it.

So if a specific and unique point in time could be signified by "date" or "datetime" then what would I call these specific but reoccurring points in time?

Answer 1

You could try

Recurrent - returning or happening time after time

Or

Periodic - occurring or recurring at regular intervals

In a programming context, I'd favor "periodic".

Answer 2

There are 2 parts to this. First is the "start time." Second is the recurrence interval. Is that correct?

For #1, I consider words like: Date-Time-Group (DTG), Epoch, Start, Instantiation
For #2, I'd consider: Frequency, Interval, Repetition Interval, Rate, Repetitiveness