You can create a WORD (WD) index on a LONG VARCHAR (CLOB) column and use the CONTAINS predicate to search the column for string constants of maximum length 255 characters.
The CONTAINS predicate is not supported on LONG BINARY (BLOB) columns using WD indexes. If you attempt to search for a string in a LONG BINARY column with a WD index using a CONTAINS predicate, an error is returned. TEXT indexes that use an external library support CONTAINS on binary data.