It is common to have working content that doesn’t presently have a place in the script. To save content for later, highlight the relevant text and go to History > Graveyard > Cut to Graveyard. The first time this happens, the Graveyard will open automatically to show that the text has been placed there.
To return to the Graveyard again later, go to History > Graveyard > Open Graveyard.
Shortcuts for the Graveyard:
Command/Control-Shift-X = Cut to Graveyard
Command/Control-Shift-C = Copy to Graveyard
Command/Control-Shift-G = Open Graveyard