Please refer to the BIX user guide - https://docs-previous.pega.com/bix-71-user-guide

Use Last Updated Time as Start For classes that include the property pxCommitDateTime, select this check box to extract all data that was created or updated since the last time the Extract rule was run. This field is not relevant until the Extract rule has run at least once. Note: If you select the incremental extraction option, a filter condition is automatically included during an extract that restricts extraction to class instances where the pxCommitDateTime property value is greater than or equal to the last date and time when the extract ran. pxCommitDateTime is automatically set for each class instance when it is changed in the database by the Pega 7 Platform database regardless of how the data was created or changed (interactively by an end user, programmatically by an activity, through an import, or by any other means). This condition is added to any others you specify on this tab. Sometimes the pxCommitDateTime property may need to be added as a database column to the class table. For example, it is not added automatically on upgrades. An extract using the incremental extraction property will fail if this column does not exist in the class table. Also note that when incremental extraction is performed, class instances with NULL values of the pxCommitDateTime property will be skipped and when using the -c command line option to extract from child classes, those child classes whose class tables do not include the pxCommitDateTime property will be skipped. Do not select this check box if you plan to run the Extract rule using the command-line and intend to use the -d, -D, -u, and -U parameters. This is because these parameters do not override the check box setting , which can result in unanticipated results from a command-line extract.