The grid is a list of all the data you have loaded or created.
There are four columns of information:
ID - The unique entry number of the row in the grid.
Lib - The name of the library (MSP file) that the row came from.
Depending on your settings this column will have one of two values (see below).
Lib Index - The block number of this row with it's library.
These values will only be continuous if there were no load errors.
Name - The value of the Name [Key, Value] line. Otherwise known as the name of the entry.
The entries in the Lib column are either a letter alllocated in the order that a library was loaded or an abbreviated version of the libarary filename.
Hang your mouse over the cell for a tooltip showing the file path as well.
The one exception to this rule is when you make a New entry. This is always allocated the identifier of User
If you change the library content in anyway then an * is appended to the end of the Lib value. This is a hint that the library has changed.
You can right click on a grid entry as a shortcut to some actions. [Move Entries]
And the screenshots below are for two of the example libraries loaded and one User entry, without and with long file name setting.

or 