Crossword puzzle clue "fixed starting point for measurements"

Fixed starting point for measurements

Starting point of a story where the ending point is, I guess, you're wearing riches

Long-distance service with fixed rates for fixed zones

Starting a project ... and what the letters between the starting and ending pairs of letters in each starred answer are doing?

Point in time fixed by some great event

A fixed point in time

Turns on a fixed point.

Any point of the compass — fixed line on a chart