What happens when the option to "copy unmatched text" is unchecked in the RegEx tool?

When the option to "copy unmatched text" is unchecked in the RegEx tool, unmatched values in the input data will not be included in the output, resulting in those fields being empty. This means any part of the text not matching the specified pattern will not contribute to the output set, thereby leaving those unmatched entries as blank or null.

This behavior allows for a cleaner output when only relevant matches are desired and is particularly useful when the goal is to focus explicitly on that matched data. The output will effectively disregard any part of the input that does not conform to the pattern, creating an output dataset that contains only the information that meets the defined criteria.

In contrast, if "copy unmatched text" were checked, the unmatched values would be retained and included in the output, possibly leading to a mix of blank and matched rows, depending on the remaining text. Thus, when it is unchecked, the outcome is that unmatched values remain empty or null in the resulting dataset.