alt-title-type Type of Alternate Title

Reason for or purpose of an alternate title (for example, “toc” for a title used in a Table of Contents, “right-running” for a right-running-head title for print).
OPTIONAL on element: <alt-title>
Value Meaning
Text, numbers, or special characters A word or phrase describing the rationale for this version of the title, for example, “right-running-head”.
Restriction This is an optional attribute; there is no default.