att.ascribed provides attributes for elements representing speech or action that can be ascribed to a specific individual. [3.3.3 Quotation 8.3 Elements Unique to Spoken Texts]
Moduletei — The TEI Infrastructure
Memberschange incident kinesic move pause q said setting shift sp spGrp stage u vocal writing
whoindicates the person, or group of people, to whom the element content is ascribed.
Status Optional
Datatype 1–∞ occurrences of 

<rng:ref name="data.pointer"/>
separated by whitespace

In the following example from Hamlet, speeches (sp) in the body of the play are linked to castItem elements in the castList using the who attribute.

<castItem type="role">
 <role xml:id="Barnardo">Bernardo</role>
<castItem type="role">
 <role xml:id="Francisco">Francisco</role>
 <roleDesc>a soldier</roleDesc>
<!-- ... -->
<sp who="#Barnardo">
 <l n="1">Who's there?</l>
<sp who="#Francisco">
 <l n="2">Nay, answer me: stand, and unfold yourself.</l>

For transcribed speech, this will typically identify a participant or participant group; in other contexts, it will point to any identified person element.