Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/EFR32MG24A010F1536GM40/SEMAILBOX_S_HOST/TX_HEADER#0x0
A write access to this register will be mapped to the TX FIFO (only for header).
TXHEADER
https://github.com/cmsis-svd/cmsis-svd-data