Working in Blender - Mastering Blender - page 12

Figure 1-11 The menu entry for a datablock with no users
Datablocks with no users do not persist when you close and reopen Blender. If you save the file now and
reopen the same file, then look again at the same drop-down menu, it will appear as shown in Figure 1-12 . The
Material entry will be gone. This is a form of Blender's garbage management, which keeps .blend files from
becomingbloatedwithunuseddata.BecauseBlenderdoesnotexplicitlydeleteadatablock,itcanbefrustrating
to track down and delete every user. However, you can delete a datablock from all its users by holding Shift
while clicking the X to remove it, thus guaranteeing its deletion when you save and reload.