| Having cotidal points means they reach high tide at the same time and low tide at the same time. |
| The difference of cotidal phase from the phase of a reference tide is the epoch. |
| The reason for these exceptions lies in the behaviour of the cotidal lines linking two amphidromic points. |
| The amphidromic point is at once cotidal with high and low waters, which is satisfied by zero tidal motion. |
| Lines of constant tidal phase are called cotidal lines, which are analogous to contour lines of constant altitude on topographical maps. |
| A region surrounding an amphidromic point from which radiating cotidal lines progress through all hours of the tidal cycle. |
