★What do the 5 Xref options mean in the External Reference Manager

Issue:

When attaching an external drawing as reference, there are 5 options in the External Reference Manager, which are Attach, Unload, Reload, Detach, and Bind. 

What do they mean respectively?

Solution:

• Attach
  Clicking this button will activate the Attach External Reference dialog box, where you can add a new external reference.
  
• Unload
  Temporarily disable the external reference, not displaying it on the screen and keeping it from participating in regeneration, in order to improve the performance. However, the external reference still exists in the main graphics file and can be displayed by selecting it and clicking the Reload button.
• Reload
  Update the external reference in the latest version.
• Detach
  Delete the external reference that you no longer need in the list box.
• Bind
  Turn the selected external reference into a block of the current drawing, so as to permanently bind the external reference into the current drawing.