Hi Can anyone explain below code

Temp_Calendar_Range:
LOAD
Num(Date#(Min(Period), 'YYYYMM'))as MinDate,
Num(Date#(Max(Period), 'YYYYMM')) as MaxDate
RESIDENT [Main Data];

//--- Assign the start and end dates to variables
LET vMinDate = Peek('MinDate', 0, 'Temp_Calendar_Range');
LET vMaxDate = Peek('MaxDate', 0, 'Temp_Calendar_Range');
DROP TABLE Temp_Calendar_Range; // Cleanup

[Master Calendar]:
LOAD DISTINCT
Year(Temp_Date) * 100 + Month(Temp_Date) as [Period],
Year(Temp_Date) as [Year],
Month(Temp_Date) as [Month],
Date(Temp_Date, 'YYYY-MM') as [Year - Month],
'Q' & Ceil(Month(Temp_Date) / 3) as [Quarter]
;
LOAD DISTINCT
MonthStart($(vMinDate) + IterNo() - 1) as Temp_Date
AUTOGENERATE (1)
WHILE $(vMinDate) + IterNo() - 1 <= $(vMaxDate);
//--- Remove the temporary variables
LET vMinDate = Null();

LET vMaxDate = Null();

Thanks in advance,

Madhu