What effect on the result-set does setting YES LIKE to true have?

In other words, what is the definition of "nearest match" in this IB Objects context?

E.g. with YES LIKE true and searching for 'ab' which words would be precluded?

Does this mean 'Starting with ...' or does it mean soundex or a certain Levenstein edit
distance or what?
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Raymond Kennington
Programming Solutions
W2W Team B