A checklist is a set of questions put together in at least one group. When category mode is enabled for a checklist, the technician does not need to answer all questions in a category to move on to the next category.  This option gave the mechanic the freedom to navigate between different group of questions, therefore allowing you to answer questions in the order that you wish.

After selecting a checklist with this mode enabled, the groups it contains will be listed.

Click the button with the group name that has the question you want to answer. Once answered, then click back button to move back to return to the list of groups. 

The color of the button will be updated with the same color of the question in that group with the most critical status.

You can also skip  a group of questions by simply clicking the x button.