HelenOS sources

ETH_10M           309 uspace/drv/nic/e1k/e1k.c 	info->ethernet_support[ETH_10M] = ETH_10BASE_T;
ETH_10M          1391 uspace/drv/nic/rtl8139/driver.c 	info->ethernet_support[ETH_10M] = ETH_10BASE_T;
HelenOS homepage, sources at GitHub