Topo map symbols

[El]

I have a Maptech CD set. I am researching an area that we will be hunting and am identifying buildings and mine locations. My question is, why are some buildings on topo maps identified in red and some in black. I think I read some where that when maps are redrawn and the older building that are no longer present, the newer map will show it in red.I can't seem to find that information but if that is true then I will hopefully have building locations identified dating to the mid 1800's. Sure hope someone here can help me out.

Thanks,

El

 

[LabradorBob]

That is my understanding also El,
That the ones in red are a building that was once there!

LabradorBob

 

[El]

Thanks Bob. I thought I had read that some where. Sure happy you verified it.

Thanks again,

El

 

[Tin Fin]

On some maps, the red or purple buildings are images of things that are there now, that were not there when the map was originally published; and, have been found from aerial photographs being taken, but have not been verified "in the field" yet.