: This likely refers to specific time blocks (e.g., 18:00 to 31 minutes past the hour) or a day-range update cycle (days 18 through 31) for habit solidification.
In police or probation reporting, "FU" can stand for Follow-Up on a specific lead or a person under supervision. fu 10 day watching
Your cervical mucus changes dramatically during the 10-day window. : This likely refers to specific time blocks (e