You configure the filter with the parameters you need. For example if you needed a parameter called Hello with a value of World:
<add Hello="World" type="ConsoleApplication22.AdministrativeFilter, ConsoleApplication22, Version=220.127.116.11, Culture=neutral, PublicKeyToken=null"
Then you just have the Filter pull out the value you need:
public AdministrativeFilter(NameValueCollection nvPairs) : this("AdministrativeFilter")
foreach (var key in nvPairs.AllKeys)
if (string.Compare(key, "Hello", StringComparison.OrdinalIgnoreCase) == 0)
helloValue = nvPairs[key];
Your response makes me ask a few questions. Is your Custom Filter just for severity? Enterprise Library already allows categories and trace listeners to have built-in severity filters without the use of a Custom Filter. Also, your definition
of severity ("error, general, exception") doesn't match with the severities that Enterprise Library is already using. Do you actually intend these to be categories?
Enterprise Library support engineer