This might be misleading, as that could be understood to mean the value attribute. While the name + value are included for a <button> or <input type="submit">, that's not the case for an <input type="image"> (i.e. value is unused and instead you get two entries for the x/y coordinate).

Maybe we could say something like ..., its value(s) will be included ..., wdyt?

Or we could split it into two sentences, like on the Submit button page. Or perhaps keep the original wording but have will be included link directly to the relevant Form data entries heading on the Submit button page.

I changed the wording slightly.

Hmm, that's still not quite accurate, as name-less image inputs will add entries to the form data set. e.g. clicking <input type="image" /> will yield something like x=123&y=234

How about this wording tweak, which also adds an example for the common case?

A {{Glossary("submit button")}} that is a member of the `form`. If the `submitter`
has a `name` attribute or is an `{{HtmlElement('input/image', '<input type="image">')}}`,
its data [will be included](...) in the form data set (e.g. `buttonName=buttonValue`).

will be included would link directly to the relevant explainer on the Submit button page.