Masking characters, otherwise known as "wildcard" characters, offer a way to make a search more flexible. They do this by increasing the number of text documents that are found by a search.
DB2 Net Search Extender uses two masking characters: percent (%) and underscore (_).
SELECT AUTHOR,TITLE
FROM DB2EXT.TEXTTAB
WHERE CONTAINS(COMMENT, '"thr%er"') = 1
This search term finds text documents containing the word "thriller".
SELECT AUTHOR, TITLE
FROM DB2EXT.TEXTTAB
WHERE CONTAINS(COMMENT, '"th_iller"') = 1
Use wildcard characters sparingly as they can increase the size of your result list significantly, thus decreasing performance and returning unexpected search results.