See also: Field Validation
Regular Expressions enable you to modify the format of entries, for example to concatinate or truncate entries
This is done using the Regular Expression option in the Query's Format dialog.
Here are a couple of examples you can unzip experiment with.... [download]
One does a simple truncation.
The other truncates, and then adds an ellipsis '...' to the end if it had to truncate (but if the original string was already short enough, it doesn't add the dots)
Go to your Query, and the Format dialog for the field.
Click against Regular Expression, then Import, and choose the appropriate file.
The examples are set to 25 characters, rather than 200 (mainly so you can more easily prove them when using the Test tab, in which you can play with the Input and see the Output calculated live).
You can adjust them to suit, by looking in the Regular Expression dialog's Settings tab, and changing the 25 you see in the Pattern field.