SUB_NAME LIKE '%Southridge%'
SUB_NAME LIKE '%Southridge'in the Where box not the top box that you are questioning about. The field that you are asking about is determined by the display field in ArcMap for that particular layer. So in ArcMap if you go to the layer properties and then display tab you will see (in v10) Display Expression then field. What this means is a published map service is that field is used as
Shorthand for a literal search text on the display field, equivalent to: where YourDisplayField like '%SearchText%'.The search expression of '%something%' means that you are expecting any number of character in front of and after the something string. So if your SUB_NAME field has the exact value of "Southridge" than there is no need for the like and wildcards.