PPS signal about CW25 GPS Receiver

[Jackwin]

Hi,
Is there anyone who has the experience in CW25 GPS Receiver?
Now i am using CW25 to make PPS synchronization with MCU and CPLD but there is no specific details about PPS in the manual.
My questions are the followings:
1. If the pps is invalid, CW25 will give a pps signal or keep the signal is low?
2. If the pps is invalid, is it earlier or later than the accurate PPS?

Hoping for your reply!

Thanks a lot！