Mapping is the activity of starting with a document and describing to the system how the document should be interpreted. Mapping is almost always done in an iterative manner. In nearly every case, the text of the document itself determines how mapping is to be done. At the point of mapping, the analyst chooses naming conventions. Naming conventions are an important aspect of mapping. Another consideration of mapping is system performance. In particular, the mapper must be careful with date standardization, taxonomy occurrences, proximity variables, and homographs.