The block dialog interprets a block and it's various fields.

block.png

At the top of this dialog is the "File Range Control". The file range control gives you a quick graphical view of where in the file this block is located.

The block trailer dialog includes an interpretation of the fields of the block trailer structure. They include:
Below the block trailer is the contents of the block. External blocks are "decoded" according to the encoding type in the header, so the bytes you see aren't the exact same bytes found on disk in this case. You can choose how to view the bytes; in hex, binary, or as a unicode string.