The Stemsize property defines the maximum number of characters used as a root word in the natural search index. The default value of this property is 5. Highly technical documentation, where longer search terms are common, may benefit from a longer stem size.
The ConfidenceLevel property defines the number of characters (as a percentage of the total) that are added to the root word to create a new word group when building natural language search indexes. The default value for this property is 33. That is, 1 character is added to the root word for every 3 additional characters in the word. Some international languages, where lengthy suffixes are common, may benefit from a higher percentage.