Term for HTML attributes without a value

Question

Is there a term used to describe the syntax for HTML attributes with missing values?

eg

<td nowrap>
<td nowrap="nowrap">

Answer 1

They are called Boolean attributes, according to the spec. See http://w3c.github.io/html/infrastructure.html#sec-boolean-attributes

Answer 2

These attributes are called boolean attributes. https://www.w3.org/TR/2008/WD-html5-20080610/semantics.html (see section 3.2.2).

Not to be confused by attributes having boolean values.