HelenOS sources

ETH_10BASE_T      309 uspace/drv/nic/e1k/e1k.c 	info->ethernet_support[ETH_10M] = ETH_10BASE_T;
ETH_10BASE_T     1393 uspace/drv/nic/rtl8139/driver.c 	info->ethernet_support[ETH_10M] = ETH_10BASE_T;
HelenOS homepage, sources at GitHub