From Help On Line:
Some FileMaker Pro features (like calculation and summary fields, and find requests) include all the values in a repeating field. For example, when you create a find request, FileMaker Pro searches for values in all repetitions, even those that aren't visible in the current layout.
I suggest explaining why you are using a repeating field. There are alternatives to repeating fields that almost always turn out to be teh better option. (Repeating fields are a legacy feature in FileMaker best reserved for only a few specialized uses.)