Hi Biren,
I haven't seen an entity yet that would provide what you are looking for. the information is not stored in tables and is calculated dynamically even inside form when displayed.
You may be familiar with purchase line tab which displays open quantity, received, invoiced etc. Actually those are methods written on sales line that fetches data from invoice tables, receiving tables at run time and then display the appropriate values. What's invoiced remains in VendPackingSlipTrans tables only.
Here is what you can do.. best entity would be purchase line. It should have ordered qty, remainInventPhysical. What you can do is do calculation out there and see if that gets you required data. The only problem i see is canceled quantity as that's not tracked anywhere in the system.