/// <summary>処理年月の初期化</summary>
/// <param name="closingDay"></param>
/// <param name="yearMonth"></param>
/// <returns></returns>
public bool InitializeYearMonth()
{
var closingDay = YearMonth.Day;
dt0t = YearMonth;
dt0f = YearMonth.AddDays(1).AddMonths(-1);
dtprt = dt0f.AddMonths(0).AddDays(-1);
dt1f = dt0f.AddMonths(1).AddDays(0);
dt1t = dt0f.AddMonths(2).AddDays(-1);
dt2f = dt0f.AddMonths(2).AddDays(0);
dt2t = dt0f.AddMonths(3).AddDays(-1);
dt3f = dt0f.AddMonths(3).AddDays(0);
dt3t = dt0f.AddMonths(4).AddDays(-1);
return(true);
}