Hi Subbu, A Qualifier allows a field to maintain different type of data.For example ,if 'date' is a field with quilifier ,then that date field can hold a) creation date b)sold date c)delivery date etc....
Why Does My Mucus Change Color? If you've ever stopped to look at the contents of the tissue after you've blown your nose, you may have noticed that your mucus isn't always perfectly clear. It may be yellow, green, or have a reddish or brownish tinge to it. What do those colors mean? You might have heard that yellow or green mucus is a clear sign that you have an infection, but despite that common misperception, the yellow or green hue isn't due to bacteria. When you have a cold, your immune system sends white blood cells called neutrophils rushing to the area.
Green mucus begins when a white blood cell interacts with bacteria and kills the cell. Once dead, certain types of white cells release a green colored pigment that blends with the mucus giving it a green hue. With green mucus, you may also experience inflamed sinuses, fever, and sinus pressure or headache.