If the application is heavily database oriented, you
include in 2.3 the data structure.  For example,
here is a student database:

<p>
  student(first-name, last-name, SSN, address)
<p>

The data elements dictionary contains the following
entries:

<p>
   address:  student
<br>
   first-name:  student
<br>
   last-name:  student
<br>
   SSN:   student
<p>

In other words, the dictionary contains all the data
elements used in the database 
as well as where it is
used (in this case, the "student" relation).

<p>
Note: If your application is not heavily database oriented,
you may replace the data structure by the information
structure produced from the data flow diagram.
The data elements dictionary then contains
attribute names used in the classes, or variable
names used in program modules.