initialising Memory Card - won't this erase the Map? How to maintain tom tom application

chunky helen
chunky helen Registered Users Posts: 2
Apprentice Seeker
edited January 2019 in Built in car navigation
Tom Tom inbuilt (mazda), fine for 3 days. Currently location is wrong, so inserted memory card to see if a GPS fix would resolve the problem. received the message I need to initialise the memory card. Have seen similar posts with instructions, but I ask the obvious question. Initialising the card effectively Wipes it clean. How does Tom Tom recognise this wiped card and re-provide the maps?
Seems strange.