a system allows for sequential treatment of sections of a zone . access to each portion can be with a sliding sleeve that has a specific internal profile . pump down plugs can be used that have a specific profile that will make a plug latch to a specific sleeve . pressure on the plug when latched allows a sequential opening of sleeves while zones already affected that are below are isolated . the pump down plugs have a passage that is initially obstructed by a material that eventually disappears under anticipated well conditions . as a result , when all portions of a zone are handled a flow path is reestablished through the various latched plugs . the plugs can also be blown clear of a sliding sleeve after operating it and can feature a key that subsequently prevents rotation of the plug on its axis in the event is later needs milling out .