There are two types of performance counter categories: single-instance and multi-instance. By default, a category is single-instance when it is created and becomes multi-instance when another instance is added. Categories are created when an application is set up, and instances are added at run time. In the .NET Framework version 1.0 and version 1.1, it is not necessary to know whether a performance counter category is multi-instance or single-instance. In the .NET Framework version 2.0, the System.Diagnostics.PerformanceCounterCategoryType enumeration is used to indicate whether a performance counter can have multiple instances.
The performance counter category can have multiple instances.
The performance counter category can have only a single instance.
The instance functionality for the performance counter category is unknown.