Unit of memory in Web UI and explanation

[Tridib Samanta]

Hi,
I can see many memory related matrices in drillbit's web UI. For example: 
Maximum Direct Memory, heap.init, heap.init etc. What's unit of these 
measurements? (KB/Byte?). Could you please point me to the document which 
describes all the metrces in the Web UI?
 
Thanks & Regards
Tridib