You have created a block in a file by itself, but have some other pieces of geometry in the file that you want to keep there for “safe keeping”. You select the geometry you want to turn in to a block, run block, name it, save it etc and close the file.
You then open another file that you want to insert this block in to. You run Insert, and find the file with that block – which comes in carrying with it the geometry that you didn’t want to be part of the block that you had not selected when you ran the block command.
Should that extra unselected geometry not have been included?
If this is as it should be then does that mean that when you are creating a block you must not have anything else in the file that you do not want to be part of that block? Even things on layers that are hidden, or on layers that are turned off?
Anotherwords, should a block be in a file that’s totally “pristine” and has nothing but the block in it?