As sub clip is a portion of a master clip that you want to isolate a portion of to use.

It's useful if you have a lot of footage and want to make specific notes about portions of the master clip

Double click a master clip to load into the source side

Then mark and In Point and an Out Point on the master clip

marking the section of the clip you want to isolate into a sub clip

Then grab the icon in the upper left corner to drag into your bin

Shown here you can drag the master clip icon to your

with in and out point marked and it will create a subclip in the bin

This is the icon of a subclip


This is the icon of a subclip

Master clip and a

Linked Master clip