WordDict maps strings to unique identifiers and frequency in the inverted index. Whenever a new word is found, the WordDict class can be asked to assign it a serial number. When doing so, an entry is created in the dictionary with a frequency of zero. The application may then increment or decrement the frequency to reflect the inverted index content.
The serial numbers range from 1 to 2^32 inclusive.
A WordDict object is automatically created by the WordList object and should not be created directly by the application.