Convert to pointer format?

Dear All,
I'm new S7 user,my experience with S7 is very less,I tried to study many thread about SLD (Shift left DWORD) and Pointer in many
forum but it not quite clear.I strucked in SLD ( convert to Pointer format) command.I don't know How does it become to pointer format.
Who have any idea and simple code to explain me about this topic.It's would be nice.I registed member to this Web just only one aim that I want to clearify about pointer.Thank you in advance.

Best regards,
Ong
:site:

Pointer points the bit. So bits 2,1 and 0 (values: 4,2 and 1 = from 0 to 7) points the bit between the byte. If you like point byte, word or dword, those 3 bits must be false and the other part points the byte in the memory space.

Have a look at the following post, it may help

http://www.plctalk.net/qanda/showpost.php?p=222839&postcount=6