When the system starts up, the user is presented with the window named "Logon." It contains two fields - Username and Password. The user has to fill in both fields and then press the OK button.

A correct entry of Username and Password results in the Main Menu being displayed. However, an incorrectly entered Username and Password results in a dialogue box being displayed which reads "Invalid Username or Password" and then it returns the "Logon" window with both fields cleared.

The user might click on the Cancel botton if he/she wants to clear all entries.

Note that when the password is entered, asterisks are displayed instead of the entered characters.

Purpose: To prevent unauthorized people to have access to the system

Inputs:

• Mouse Action(mouse control from users)
• Username
• Password

Outputs:

• None

Calls:

• Main Menu

Called by:

• None

Error conditions:

• Invalid combination of username and password

Algorithm:

if user clicks on 'cancel' button
  then clear all entries
else if user clicks on the 'OK' button
  then check if combination of username and password is valid
  if valid
    then calls Main Menu Module
  else 
    print_to_user "Invalid username/password"
    displays the logon interface again
  endif
endif

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