Page Header DB Frag ID Property

Question

I am using SQL Server version: Microsoft SQL Server 2012 - 11.0.2100.60 (X64).

I created a single table containing one and only one integer-valued column. I then added one and only one row to the table.

CREATE DATABASE SQLServerInternals;
GO

USE SQLServerInternals;
GO

CREATE TABLE page_header
(
    c1 INT IDENTITY NOT NULL
) ON [PRIMARY];
GO

INSERT INTO page_header DEFAULT VALUES;
GO 

DBCC IND(SQLServerInternals,page_header,1);
GO
DBCC TRACEON(3604);
GO
DBCC PAGE (SQLServerInternals,1,231,2);
GO

Here is the output from DBCC PAGE.

Does anyone know what the DB Frag ID = 1 means and whether it is the value 0x0100 that I see in bytes 64-65? I assume that the value is at most a SMALLINT type. I assume that the remaining bytes are for "future use".