A few features of the XMLUI submission user interface, such as the deposit license text, can be marked up using a subset of HTML.  Only these elements may be used:

• h1
• h2
• h3
• h4
• h5
• p
• a
• b
• i
• u
• ol
• li
• img

Do not try to make the content into a complete HTML document.  It is just a fragment which will be textually inserted (not framed) into a larger document.