The following markers could be set:
// General markers
###URL_SELF###
###IMAGE_PATH###
###INFO###
// Menus
###MENU_MODE###
###MENU_PERIOD###
// Show the value of db fields
######
// Show information about the frontend user (if cruser_id is not "0")
###FE_USER_###
// Show the value of form input fields
###VALUE_###
// Show whole prepered form content
###INPUT_HTML###
###INPUT_PLAIN###
// Show your own locallang labels (see manual)
###LLL:###
// Show backend user information
###USER:###