ulink.hyphenate — Allow URLs to be automatically hyphenated
If not empty, the specified character (or more generally, content) is added to URLs after every “/”. If the character specified is a Unicode soft hyphen (0x00AD) or Unicode zero-width space (0x200B), some FO processors will be able to reasonably hyphenate long URLs.
As of 28 Jan 2002, discretionary hyphens are more widely and correctly supported than zero-width spaces for this purpose.