Which API Version is "Included" in Arduino ESP32 Core?


I was wondering how one relates the official ESP32 API documentation to what is provided in the Arduino ESP32 core. There appears to be some disconnects. For example, the API documentation for the ledc_timer_config_t datatype includes a field called clk_cfg.
However, the definition of that datatype in file 'ledc.h' of Core 1.0.6 does not include that field:

 * @brief Configuration parameters of LEDC Timer timer for ledc_timer_config function
typedef struct {
    ledc_mode_t speed_mode;                /*!< LEDC speed speed_mode, high-speed mode or low-speed mode */
    union {
        ledc_timer_bit_t duty_resolution;  /*!< LEDC channel duty resolution */
        ledc_timer_bit_t bit_num __attribute__((deprecated)); /*!< Deprecated in ESP-IDF 3.0. This is an alias to 'duty_resolution' for backward compatibility with ESP-IDF 2.1 */
    ledc_timer_t  timer_num;               /*!< The timer source of channel (0 - 3) */
    uint32_t freq_hz;                      /*!< LEDC timer frequency (Hz) */
} ledc_timer_config_t;

So, does the Arduino ESP32 Core "include" a DIFFERENT version of the API?

PS -- I've also posted this question in the ESP Arduino Forum.

The ESP-IDF version is referenced on the "releases" page on GitHub: Releases · espressif/arduino-esp32 · GitHub

It looks like version 1.0.6 of the Arduino Core is based on version 3.3.5 of the ESP-IDF.