TP Memory Modules

[<Robert_Huber_at_WYATT__1CALL__WDC@wellspringres.com>]

     There was some discussion a few weeks ago about stacked memory and 
     that using stacked memory was not a good idea. What I'm wondering is 
     what are the visual clues indicating that stacked memory is being used 
     in a given memory module? I ask this because I've gotten odd responses 
     from sales people when I ask if the memory modules they are selling 
     have stacked memory? Is there another term for this type of memory?
     
     Thanks.