I'm using l99dz100g in my project , anyone konw how to trig the wwdg ?

[LYU.11]

Datasheet said "Subsequently, the micro controller has to serve the watchdog by alternating the watchdog trigger bit TRIG (CR1,Config Reg) within the safe trigger area TSWX."

Confuse what is the "alternating"​ meaning. CR1 CFG ==1 , CR1,CFRG==0....? or CR1=1,CR1=0,CFGR=1,CFGR=0?