You can create subclips anywhere that you have access to the source clip (i.e. Thumbnail, Player, Triptych and Source-Sequence viewers).
To create a subclip in the player:
The start of the sub-clip is marked.
The end of the sub-clip is marked.
The section of the clip that is between the In and Out marks is the sub-clip.
The subclip is created as a new clip in the Media library. It has the original name and append ("_Subclip_") with an incremented number, starting with ("001").