Undocumented attributes - mat-subheader, mat-line, mat-list-icon

I am looking at the example source code of List component on this page: https://material.angular.io/components/list/examples and am a bit confused as to where some of the used attributes come from.

The example looks like this:

<mat-list>
  <h3 mat-subheader>Folders</h3>
  <mat-list-item *ngFor="let folder of folders">
    <mat-icon mat-list-icon>folder</mat-icon>
    <h4 mat-line>{{folder.name}}</h4>
    <p mat-line> {{folder.updated | date}} </p>
  </mat-list-item>
  <mat-divider></mat-divider>
  <h3 mat-subheader>Notes</h3>
  <mat-list-item *ngFor="let note of notes">
    <mat-icon mat-list-icon>note</mat-icon>
    <h4 mat-line>{{note.name}}</h4>
    <p mat-line> {{note.updated | date}} </p>
  </mat-list-item>
</mat-list>

I can’t find documentation about the mat-subheader attribute used in the example, as well as mat-line and mat-list-icon. Is there any? I just started to use Angular, so I could as well be overlooking something.

[thw0rted]

@devversion Looking back at the OP, maybe the actual resolution is that this is effectively a duplicate of #3125. That issue more directly address the problem.

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