Use the EventSourceCreationData.CategoryCount and EventSourceCreationData.CategoryResourceFile properties to write events with localized category strings. The Event Viewer displays the category for an event entry if you supply a category when you write the event. Event log categories are application-defined strings that help filter events, or provide further information on the event. For example, your application can define separate categories for different components or different operations.

Event categories are optional; if your application does not use categories, do not set the EventSourceCreationData.CategoryCount and EventSourceCreationData.CategoryResourceFile properties.

For details about defining event messages and building event resource files, see the "Message Compiler" topic in the Platform SDK documentation at tp://msdn.microsoft.com/.