ada-tab-policy

ada-tab-policy is a variable defined in `ada-mode.el'.
Its value is

indent-auto

Documentation:
Control the behavior of the TAB key.
Must be one of :
`indent-rigidly' : always adds `ada-indent' blanks at the beginning of the line.
`indent-auto' : use indentation functions in this file.
`always-tab' : do `indent-relative'.

You can customize this variable.