Found registry entries can be grouped by safety level or level of user experience.
There are three levels, each level suppose an experience value user should have to safely correct those entries.
- Safe, or Regular user experience;
- Caution or Moderate user experience;
- Extreme Caution or Advanced user experience.
Levels have different icons displayed when the list is grouped by error category or by filter.
or 
Safe icon (Regular user experience).
Entries are safe to correct with default suggested
correction.
or 
Caution icon (Moderate user experience).
Modifying these entries without reviewing
may cause problems. Please check suggested corrections.
or 
Extreme caution icon (Advanced user experience).
Modify these entries only if you are sure how
to correct them. Note: Really unsafe entries are in the excluded
lists and not displayed.
Caution and extreme caution flags do not mean critical errors. They only mean that user should carefully check all automatically suggested corrections for those invalid entries. This is for advanced users. Other users knowing a little about the Windows registry may simply leave yellow and red entries without changes. By default such entries are not selected for corrections - no selection marks in the related checkboxes.