220.127.116.11. Launch and Latch Edges
The launch edge of the clock signal is the clock edge that sends data out of a register or other sequential element, and acts as a source for the data transfer. The latch edge is the active clock edge that captures data at the data port of a register or other sequential element, acting as a destination for the data transfer.
You must define all clocks in your design by assigning a clock constraint to each clock source node. These clock constraints provide the structure required for repeatable data relationships. If you do not constrain the clocks in your design, the Intel® Quartus® Prime software analyzes all clocks as 1 GHz clocks to maximize timing based Fitter effort. To ensure realistic slack values, you must constrain all clocks in your design with real values.