This keyboard consist of 4 layers. First two layers are the same as normal Inscript or Remington.

layer one - Direct key

layer two - shift + key

layer three - AltGr+key (AltGr = Right side Alt)

layer four - AltGr+shift+key

You can see the layout image below, in that

• left bottom - layer one
• left top - layer two
• right bottom - layer three
• right top - layer four
  

example

In Extended Inscript layout
In case of ’d’,
’d’ gives ്
‘Shift+d’ gives അ
‘Right Alt+d’ gives ഽ
‘Right Alt+Shift+d’ gives ഁ