Custom Fields and Extended properties - Are they Same?

问题

There is an option to "Add a custom field" in Google Contacts web page, when we create/edit a contact.

Using Google Contact API v3.0, we can add "extended properties" using 'gd:extendedProperty' xml-element.

Are these two pointing to the same field. When I create an extended property via API, I am not seeing that field/value in the Google contacts web page view.

I get a feeling that, the gd:extendedProperty is solely for API based manipulation purpose. Is it right?

In that case, is it possible to create a "Custom Field" via API and I want that field/value to be shown in the Google Contacts web page.

来源：https://stackoverflow.com/questions/32802382/custom-fields-and-extended-properties-are-they-same