gist access methods parameter types

If I have this sql composite type:

CREATE TYPE d_type AS
(

i integer,

e integer,

id integer

);

and this table:

CREATE TABLE my_tab
(
d_col d_type NOT NULL
)

CREATE INDEX my_tab_d_col_gist ON my_tab USING gist (d_col);

I am implementing consistent, union, compress, decompress, penalty,
picksplit and same.
CREATE OPERATOR CLASS d_type_ops
DEFAULT FOR TYPE d_type USING gist AS
FUNCTION 1 d_type_consistent(internal, d_type, smallint, oid, internal),
FUNCTION 2 d_type_union(internal, internal),
FUNCTION 3 d_type_compress(internal),
FUNCTION 4 d_type_decompress(internal),
FUNCTION 5 d_type_penalty(internal, internal, internal),
FUNCTION 6 d_type_picksplit(internal, internal),
FUNCTION 7 d_type_same(internal, internal, internal);

The problem is that some of these methods take as input parameters the
d_type and some the struct type that I internally implemented in c (which
will be saved to the tree).
If I understand correctly consistent and compress are the only functions
that will have input parameter of d_type. The others will have my c internal
type.
*Is this correct?*
Something else, will a non-leaf node have one entry that will be produced by
union? I am asking because I want the leaf node entries to be of different
type from non-leaf node entries (the difference between them is that
non-leaf entry will not keep the id attribute).
Thank you in advance.