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You can explode an inserted block to its original component entities. When you explode a block, only that single instance of the block is affected. The original block definition remains in the drawing, and you can still insert additional copies of the original block. If you explode a block that contains attributes, the attributes are lost, but the original attribute definitions remain.
Exploding dissociates component entities to their next simplest level of complexity; blocks or polylines in a block become blocks or polylines again.