Indicates the level at which to display a section when the display level and hierarchical level are different.
| Value | Meaning |
|---|---|
| Text, numbers, or special characters | The name or number of the level of heading to be used to display this heading instead
of its regular hierarchical level. This attribute was added to preserve material that
may already exist in tagged documents, so the values are likely to be specific to
an individual publisher or tag set. Examples might include 2, head-2, level2, etc. |