The NVIC_ICPR removes the pending state from interrupts, and shows which interrupts are pending. See the register summary in Table 4.2 for the register attributes.
The bit assignments are:
Interrupt clear-pending bits.
0 = no effect.
1 = removes pending state from interrupt.
0 = interrupt is not pending.
1 = interrupt is pending.
Writing 1 to an NVIC_ICPR bit does not affect the active state of the corresponding interrupt.