# Editing a Column Definition | Top

The column Handling dialog allows you to set options for each comparison column. A subset of this dialog is used to set default handling for all columns. Mark the Key checkbox to make data in this column control sorting and alignment. If you have more than one key column, the priority for sorting is granted to the top-most columns in the list. Mark the Use Default checkbox to use the default column handling as defined for this session. Pick the appropriate Type for the column:
General | Automatically determine the column type based on the data in the files.
Text | Column contains textual data.
Mark the Unimportant checkbox to indicate that this column is not important to the comparison. (Unimportant differences are colored blue instead of red, or are ignored altogether using the Ignore Unimportant Differences feature.) The Text important, except for options govern columns that are defined or detected as Text. Mark the Character case (ABC = abc) checkbox if differences in case (i.e., capitalization) are unimportant. Mark the Whitespace checkbox to consider differences in whitespace (the number of blanks before, after or between words) unimportant. Use Date tolerance to allow date-time values in this column to differ by the given amount before being considered an important difference. Set the Numeric tolerance value to allow numbers to differ by the given amount before being considered an important difference.