Before you can learn how to modify a file definition, it is helpful to know how to create a file definition.
A file definition stores information about the structure of a file, such as field names, what type of data each field holds, and which fields to index.
Note: When you create a file definition, you can copy fields and their properties (including validation and default and calculation formulas) from other files. If you want to do this, make sure the other files are open in the current window before you begin, and at step 2 deselect New Window.
To create a file definition:
1.At the Superbase window, choose File/New/File.
2.In the New File dialog box, enter a name for the new file, then click OK.
The File Definition dialog box appears.
The list in the top left of the dialog box shows other database files that are open in the current window. You can use this list to switch between file definitions. This is useful if you want to copy fields or other information from one file definition to another. You can use Copy and Paste to copy fields from these files into the file definition you're creating.
3.To add a field to your file definition, double-click in the Field Name column on a blank row, or click Add. In the Add Field dialog box, enter a name for the field, and click OK.
Note: You can use up to 15 characters in a field name, but you mustn't begin a field name with a number, or include blank spaces, or use reserved words.
4.To set the data type of the field, select one of these data types from the Data Type list:
Text
External
Decimal
Long Integer
Integer
Date
Time
5.To set the display format of the field, double-click in the Format column for that field, or click the Format button.
Superbase displays the appropriate Format dialog box for the data type of the field you selected.
6.Repeat steps 3 through 5 for additional fields you want to add.
7.To create indexes for the file, double-click in the Index column, or click the Index button. In the Index Definition dialog box, select the fields you want to use as indexes.
8.In addition, you can: assign further field properties, add validation and calculation and default formulas, add comments and status bar help for each field, rename fields, delete fields, and assign passwords for data security. For more help on these tasks, see Modifying a File Definition.
9.When you finish, click Save to save your changes to the file definition.
Superbase displays your new file in the work space.
Exercise:
Create a new file called PEOPLE to hold the names and phone numbers of PEOPLE in your organization. Add the following fields, with properties similar to these…
First_NameText15 characters
Last_NameText15 characters Indexed
Phone_NumberText20 characters Indexed
Full_NameCalculated Text31 characters Formula= First_Name + " " + Last_Name Indexed
Building NumberText10 characters
Once you have learned to create a new file definition, modification is simply a matter of opening up the file in your Superbase window (use the File, Open File command) and then selecting the command to modify the file defintion, which is File, Modify File. The File Defintion dialog will look similar to the following:

Once a file is open in the file definition panel, you can make changes to it and SAVE them, or you can CANCEL out which simply returns to the original definition of the file.