or a function symbol to call.
In the last case, we call the function with one argument,
which is a list of all the arguments given to this function.
+If the function can't decide a coding system, it can return
+`undecided' so that the normal code-detection is performed.
If OPERATION is `insert-file-contents', the argument corresponding to
TARGET may be a cons (FILENAME . BUFFER). In that case, FILENAME is a
If VAL is a cons of coding systems, the car part is used for decoding,
and the cdr part is used for encoding.
If VAL is a function symbol, the function must return a coding system
-or a cons of coding systems which are used as above. The function gets
-the arguments with which `find-operation-coding-systems' was called.
+or a cons of coding systems which are used as above. The function is
+called with an argument that is a list of the arguments with which
+`find-operation-coding-system' was called. If the function can't decide
+a coding system, it can return `undecided' so that the normal
+code-detection is performed.
See also the function `find-operation-coding-system'
and the variable `auto-coding-alist'. */);