8 Show Custom Tracking/Kerning
Turning on this Composition preference enables you to see instantly where you (or anyone else in your workgroup) have applied custom tracking, most likely for the purpose of tracking back a line to fix widows and orphans or to save space. This can be enormously beneficial if you suspect that one of your (less-typographically sensitive) colleagues has been using tracking a bit too zealously, or if the text content has been revised and the tracking that you had previously (reluctantly) applied is now no longer needed.