var bind structure member usage

[Vineet G. <vg...@np...>]

can you pls expain the usage of u_char buf[40];  void *data member of =
struct variable_list=20
while code study i could not catch mutch abt them=20
thanks=20
best regards
vineet goel

struct variable_list {
    struct variable_list *next_variable;    /* NULL for last variable */
    oid     *name;  /* Object identifier of variable */
    size_t  name_length;    /* number of subid's in name */
    u_char  type;   /* ASN type of variable */
    union { /* value of variable */
 long *integer;
 u_char *string;
 oid *objid;
 u_char  *bitstring;
 struct counter64 *counter64;
#ifdef OPAQUE_SPECIAL_TYPES
 float   *floatVal;
 double *doubleVal;
/* t_union *unionVal; */
#endif /* OPAQUE_SPECIAL_TYPES */
    } val;
    size_t     val_len;
    oid name_loc[MAX_OID_LEN];  /* 90 percentile < 24. */
    u_char buf[40];             /* 90 percentile < 40. */
    void *data;   /* (Opaque) hook for additional data */
    int  index;
};