I am a Landscape Architect. I have a very large irrigation project that I need to add the total gallons per minute (gpm) of selected head (sprinkler) symbols. Each symbol has an attribute with the gpm value already. I want to make a selection of heads, add up all the values from the gpm attribute then take the total and update another block with that total. The block with the total gpm is a tag for the specific valve that is operating the heads. I would have to be able to select the particular valve tag to update in the middle of the operation. I have been using the Express tools export attribute information and opening in Excel then getting the sum then going back to Acad and manually updating the valve tag...very tedious...over 300 valves need to be done! Any ideas?