Trace activation is a way of generating specific trace data that is relevant for your components. This reduces the amount of traces listed on the TraceViewer user interface.
All the traces that come from various components on the device are first passed onto a trace handler, called TraceCore. TraceCore then determines which traces should be handed over to the PC and which ones should not. TraceCore only passes on those traces that have been activated and ignores the rest.
To activate and deactivate traces that are in the Open System Trace (OST) format, you must first define the used Dictionary file.
Dictionary files are XML files that are usually available in your development environment. They are automatically re-generated every time Trace Compiler is run. This usually happens when you compile a component that contains Open System Trace (OST) traces. Dictionary files can normally be found from the \epoc32\ost_dictionaries directory under your Software Development Kit (SDK).