Restaurant Locations

Hello,

From the little you have told us, it seems to us that a custom field can be the good way to get what you need.
The custom field type may be order type if you want that your customer define it while checkout, or you can use address type too to define it while your customer define his address.

In order to answer you more precisely, we will need more elements, like a concrete case, description precise of needs, and what's be the data goal for e-shop manager.

We can already tell you that you have to define your custom field as "Required" in order to don't allow user to continue process without have select one custom field's value.

Have a look on this tutorial to learn more about the Custom field.
Regards