Referencing a ListItemposition from resoucrce file

I am currently working on a proximity alert Android App.There is a listItem_pos key that I don't understand how it has been declared. It's this line

   int listItemPos = callerIntent.getIntExtra(getString(R.string.listitem_pos), -1); 

In the code below. Is it done automatically when a user raises a new alert?

 private void setPreferences() {
    boolean isNewAlert = callerIntent.getBooleanExtra(getString(R.string.new_alert), true);
    SharedPreferences.Editor editor = defaultSharedPreferences.edit();

    if (isNewAlert) {       
        editor.putBoolean(getString(R.string.preference_turnon_key),false);     
        editor.putString(getString(R.string.preference_alertname_key), "");     
        editor.putString(getString(R.string.preference_address_key), "");
        editor.putString(getString(R.string.preference_radius_key), "1000");
        editor.commit();
    } else {
        int listItemPos = callerIntent.getIntExtra(getString(R.string.listitem_pos), -1); // <- here
        if (listItemPos != -1) {
            AlertEntity alertEntity = AlertListManager.getAlertEntityAtListPos(listItemPos);            
            editor.putBoolean(getString(R.string.preference_turnon_key),alertEntity.enabled);   
            editor.putString(getString(R.string.preference_alertname_key),alertEntity.name);
            editor.putString(getString(R.string.preference_address_key),alertEntity.address);   
            editor.putString(getString(R.string.preference_radius_key),alertEntity.radius);
            editor.commit();
        }
    }
}