NameValueCollection.Add Method (String, String)
Adds an entry with the specified name and value to the NameValueCollection.
Assembly: System (in System.dll)
If the specified key already exists in the target NameValueCollection instance, the specified value is added to the existing comma-separated list of values in the form "value1,value2,value3". The values are associated with the same key in the target NameValueCollection instance.
If Count already equals the capacity, the capacity of the NameValueCollection is increased by automatically reallocating the internal array, and the existing elements are copied to the new array before the new element is added.