The search character set configured for the application dictates the set of available characters for stemming and thesaurus entries. By default, only alphanumeric characters may be used in stemming and thesaurus entries. Additional punctuation and other special characters may be enabled for use in stemming and thesaurus entries by adding these characters to the search character set.

The MDEX Engine matches user query terms to thesaurus forms using the following rule: all alphanumeric and search characters must match against the stemming and thesaurus forms exactly; other characters in the user search query are treated as word delimiters.