This command provides some interpretation of backtraces generated during chunking. If no option is given, then a list of all chunks and justifications is printed.
The two most useful variants are explain name and explain name condition. The first variant lists all of the conditions for the named chunk or justification, and the ground which resulted in inclusion in the chunk/justification. A ground is a working memory element (WME) which was tested in the supergoal. Just knowing which WME was tested may be enough to explain why the chunk/justification exists. If not, the conditions can be listed with an integer value. This value can be used in explain name condition to obtain a list of the productions which fired to obtain this condition in the chunk/justification (and the crucial WMEs tested along the way). Why use an integer value to specify the condition? To save a big parsing job.
If an option is given, it must match one of the following forms:
Explain mode must be -on when a chunk or justification is created or no explanation will be available. When explain mode is on, more memory is used, and building chunks and justifications will be slower.