The Open command opens a master block, block view, or block occurrence for you to edit its graphical elements. You can, for example, create nested blocks by copying and pasting into the block, add 2D elements by drawing in the block, add and edit annotations and dimensions, and create and assign a label to the block.
All edits are made to the master block definition, whether you select the command from the Library or from an occurrence on a sheet.
All occurrences in the document are updated to display the modified graphics when you return to the active sheet.
All edits are applied to blocks in the active document only.
The Open command is available on the shortcut menu of a selected block.