In 19.319 form:xforms-submission, ODF 1.2 says:

"The form:xforms-submission attribute specifies the name of an
<xforms:submission> element for a <form:button> control."

I rather doubt that because there is no <xforms:submission> element.

We do have the attribute form:xforms-submission on <form:button> but the
question is what is it specifying a name for?

My suspicion is that it is the name for the content submitted with the
form:button is selected.

Or as I suggested to Francis:

"specifies the name of a submission by a <form:button> control."

So the submission can be referred to by the processor and returned with
that name to its producer.

But that is only speculation on my part from the text.