Missing in Action. A casualty classification assigned to combatants, military chaplains, combat medics, and prisoners of war who are reported missing during wartime or ceasefire. They may have been killed, become prisoners of war, wounded, lost at sea, or deserted. If deceased, neither their remains nor grave has been positively identified. Becoming MIA has been an occupational risk for as long as there has been warfare or ceasefire.
Two hundred fifty two soldiers from Texas were aboard the troop carrier SS Tuscania bound for France.  She was torpedoed by a German U-boat 5 Feb 1918 near the isle of Islay, U.K.  Of the 252 from Texas, 204 of them survived the ordeal, but 48 young men did not.  Two are missing in action and 46 were status of killed in action.  For full details see this website Tuscania↗.
NAME Vet's given names, MEM The place where the Vet is memorialized, linked to Find A Grave.