this is a bug?

[A Soare]

enum Lisp_Type
  {
    /* Integer.  XINT (obj) is the integer value.  */
    Lisp_Int,

    /* Symbol.  XSYMBOL (object) points to a struct Lisp_Symbol.  */
    Lisp_Symbol,

    /* Miscellaneous.  XMISC (object) points to a union Lisp_Misc,
       whose first member indicates the subtype.  */
    Lisp_Misc,

    /* String.  XSTRING (object) points to a struct Lisp_String.
       The length of the string, and its contents, are stored therein.  */
    Lisp_String,

    /* Vector of Lisp objects, or something resembling it.
       XVECTOR (object) points to a struct Lisp_Vector, which contains
       the size and contents.  The size field also contains the type
       information, if it's not a real vector object.  */
    Lisp_Vectorlike,

    /* Cons.  XCONS (object) points to a struct Lisp_Cons.  */
    Lisp_Cons,

    Lisp_Float,

    /* This is not a type code.  It is for range checking.  */
    Lisp_Type_Limit
  };


Here is a strange bug that I met 1000 times so far.

1. emacs -q

then, visiting the tags table of emacs, go to the upper listed symbol.

The first 4 members of this enum are listed in yellow color to me . The last 4 
members in black color .

This is normal?

Or this is a bug?

PS: I report little bugs and you learn me emacs lisp en échange.