TMS320F28032: what's the difference between AQCSFRC.CSFA=00 and =11?

Hi,

in datasheet, For AQCSFRC.CSFA/CSFB

00 Forcing disabled, i.e., has no effect
01 Forces a continuous low on output A
10 Forces a continuous high on output A
11 Software forcing is disabled and has no effect

1. what's the difference between 00 and 11?

2. My customer has tested with the following sentences:

a. EPwm1Regs.AQCSFRC.all = 0x05;// it can turn off both EPWM1A and EPWM1B

b. EPwm1Regs.AQCSFRC.all = 0x01;  EPwm1Regs.AQCSFRC.all = 0x05;// there will be high pulses on EPWM1B shown below, why?

3. are there any difference between writing the registers as a whole and writing by bit

writing whole registers: 

EPwm1Regs.AQCSFRC.bit.CSFA = 0x01;  EPwm1Regs.AQCSFRC.all = 0x05;

writing by bit:

EPwm1Regs.AQCSFRC.bit.CSFA = 0x01; EPwm1Regs.AQCSFRC.bit.CSFB = 0x01;