How to set BS4 Card header, etc

Oh, the inspect, that was the missing “link”. I see the ID of the image in the card was Card1_image and the src is the attribute name, so it becomes the property name of the image in the card, or Card1_image.src. (Guess I’m going to brush up on DOM some more.)

However, I also see something in the inspect that looks unusual.

<div id="Card1_text" class="card-text " style="" data-i18n="This is the text of the Card.">This is the text of the Card.</div>

the data-i18n attribute. Is this used to go back to the default value?