|Dotfuscator > Understanding Instrumentation with Dotfuscator > Instrumentation Injection > PreEmptive Analytics Custom Attributes > Shelf Life and Sign of Life Attributes|
The Shelf Life and Sign of Life custom attributes are defined in
PreEmptive.Attributes.dll, which is located by default in the Dotfuscator 4 installation folder. To add the Shelf Life or Sign of Life custom attributes to an application, the developer must add a reference to this DLL and the DLL must be available at compile time. While injecting the Shelf Life code, Dotfuscator removes references to this DLL; therefore, the DLL is not required at application runtime and does not need to be distributed with the application.
In addition to using the custom attributes DLL, the Shelf Life or Sign of Life attributes may be specified as an extended attribute using the instrumentation editor on the Dotfuscator user interface. This is useful if you do not want to modify the application source code to add custom attributes.
This section discusses the custom attribute at a high level (what it is, when and where to use it). For a programmer's reference, see the custom attribute reference.