flag 是什么意思

private int ValidateData()
        {
            int flag = 0;
            if (textBox1.Text == "")
            {
                textBox1.Focus();
                errorProvider1.SetError(textBox1, "请输入第一个名字");
                flag = 1;
            }
            if (textBox2.Text == "")
            {
                textBox2.Focus();
                errorProvider1.SetError(textBox2, "请输入第二个名字");
                flag = 1;
            }
            if (dateTimePicker1.Value > DateTime.Now)
            {
                dateTimePicker1.Focus();
                errorProvider1.SetError(dateTimePicker1, "请输入日起，它必须比现在日期早");
                flag = 1;
            }
            if (textBox3.Text == "")
            {
                textBox3.Focus();
                errorProvider1.SetError(textBox3, "请输入地质");
                flag = 1;
            }
            if (textBox4.Text == "")
            {
                textBox4.Focus();
                errorProvider1.SetError(textBox4, "请输入原因");
                flag = 2;
            }
            return flag;
        }

flag 是什么意思