scheme-indent-function
scheme-indent-function is a compiled Lisp function in `scheme.el
'.
(scheme-indent-function INDENT-POINT STATE)
Scheme mode function for the value of the variable `lisp-indent-function'.
This behaves like the function `lisp-indent-function', except that:
i) it checks for a non-nil value of the property `scheme-indent-function'
(or the deprecated `scheme-indent-hook'), rather than `lisp-indent-function'.
ii) if that property specifies a function, it is called with three
arguments (not two), the third argument being the default (i.e., current)
indentation.