MSP430-3P-AWGH-AMB8423-DEVBD: Time Required to set the flag

Part Number:MSP430-3P-AWGH-AMB8423-DEVBD

I was going through source code.

I didn't get why time equivalent to 0x47FF is required to set the flag? From where do we get to know what should be proper value of i?

//disable the XT1 clock ,which is required to avoid the XT1 low frequency fault trigger
_BIS_SR(OSCOFF); //MS

//wait till the Oscillator becomes stable
do
{
IFG1 =0;
// Clear OSCFault flag
IFG1 &= ~OFIFG;

// Time for flag to set
for (i = 0x47FF; i > 0; i--);
}