The following codes work in all three modes:

$c
  number of currently selected objects
$C
  total number of objects in folder
$sb
  total size of selected objects in bytes
$sk
  total size of selected objects in kBytes, i.e. bytes / 1000
$sK
  total size of selected objects in KBytes, i.e. bytes / 1024
$sm
  total size of selected objects in mBytes, i.e. bytes / 1000000
$sM
  total size of selected objects in MBytes, i.e. bytes / 1048576
$Sb
  total size of folder content in bytes
$Sk
  total size of folder content in kBytes, i.e. bytes / 1000
$SK
  total size of folder content in KBytes, i.e. bytes / 1024
$Sm
  total size of folder content in mBytes, i.e. bytes / 1000000
$SM
  total size of folder content in MBytes, i.e. bytes / 1048576
$fb
  free space on drive in bytes
$fk
  free space on drive in kBytes, i.e. bytes / 1000
$fK
  free space on drive in KBytes, i.e. bytes / 1024
$fm
  free space on drive in mBytes, i.e. bytes / 1000000
$fM
  free space on drive in MBytes, i.e. bytes / 1048576
$x(xxx)
  Left-oriented tabulator: print the following information at X position "xxx" (relative to the left border of the status bar).
  Example: $x(300)$sK will always print the total size of the selected objects at X position 300.
$x(-xxx)
  like before, but relative to the right border of the status bar.
  Example: $x(-150)$sK will print the total size of the selected objects at X position 100, if the status bar is currently 250 pixels wide.
$x(xx%)
  like before, but the X position will be calculated using "xx" as a percentage relative to the current width of the status bar.
  Example: $x(50%)$sK will always print the total size of the selected objects in the center of the status bar.