The WJ IV ACH online Test Record entry page has "item" buttons (see below): 

Clicking the "item" button next to a test opens the item-level data entry view: 

Entering data via the item-level view tells the online scoring and reporting platform what specific items (and the skills related to those items) that the examinee had difficulty with. 

This data is used with the WIIIP add-on subscription to generate specific formative interventions as part of a comprehensive report.