Missing C struct for IO_MUX_x_REG?

[kolban]

I have been enjoying/appreciating the C structures mapped to the registers that can be found in soc/esp32/include/soc. I was looking at the tech ref documentation on the register called IO_MUX_x_REG and seem to find this referenced in "io_mux_reg.h" ... however, I am not finding an equivalent C struct mapping. Is this be deliberate choice? Is there a technical reason that there isn't a C struct mapping to this register bank?