SDL_PenInputFlags.3type - Man Page

#include <SDL3/SDL_pen.h>

typedef Uint32 SDL_PenInputFlags;

#define SDL_PEN_INPUT_DOWN         (1u << 0)  /**< pen is pressed down */
#define SDL_PEN_INPUT_BUTTON_1     (1u << 1)  /**< button 1 is pressed */
#define SDL_PEN_INPUT_BUTTON_2     (1u << 2)  /**< button 2 is pressed */
#define SDL_PEN_INPUT_BUTTON_3     (1u << 3)  /**< button 3 is pressed */
#define SDL_PEN_INPUT_BUTTON_4     (1u << 4)  /**< button 4 is pressed */
#define SDL_PEN_INPUT_BUTTON_5     (1u << 5)  /**< button 5 is pressed */
#define SDL_PEN_INPUT_ERASER_TIP   (1u << 30) /**< eraser tip is used */
#define SDL_PEN_INPUT_IN_PROXIMITY (1u << 31) /**< pen is in proximity (since SDL 3.4.0) */

This datatype is available since SDL 3.2.0.