XkbKeyType returns a pointer to the key type in the types vector of the client map in xkb corresponding to the given keycode and group index.
typedef struct {                             /* Key Type */
        XkbModsRec              mods;           /* modifiers used to compute shift level */
        unsigned char           num_levels;     /* total # shift levels, do not modify directly */
        unsigned char           map_count;      /* # entries in map, preserve (if non-NULL) */
        XkbKTMapEntryPtr        map;            /* vector of modifiers for each shift level */
        XkbModsPtr              preserve;       /* mods to preserve for corresponding map entry */
        Atom                    name;           /* name of key type */
        Atom *                  level_names;    /* array of names of each shift level */
} XkbKeyTypeRec, *XkbKeyTypePtr;