Size of character sets and searching clue words

There is an inverse relationship between the number of characters a character set supports in an index and the number of characters in a clue word that are searched. The following table shows how many characters each character set supports in an index and the number of characters in a clue word that are searched for that character set.
Character set Max number of characters in index Number of characters searched in clue word
ASCII 62 First 24
OVERLAP_ISO 124 First 20
ISO 124 First 20
User specified 256 First 16
For example, in an index created with a user-defined character set, only the first 16 characters of a clue word are used in the search. This means that any word in the index that matches the first 16 characters of the clue word is a hit. In the following query the clue is nonintercompatibility:
select title from reports 
where etx_contains(abstract, 'nonintercompatibility');

A search returns both nonintercompatible and nonintercompatibility as exact word matches.