askForCredentialparameter for xmlaccess.sh/.bat. You can pass this parameter to xmlaccess and skip passing username and password when you do that xmlaccess script will prompt you for usernmae and password at the runtime.
This might be good option if you have build script that executes xmlaccess and you dont want to save your user name and password in the build script. Other advantage of doing that is you dont have to pass the password using visible format on the command line. Also if some one looks at the process view on the machine at the same time when your executing xmlaccess he wont see your password.