USFM declares that // is a special mark meaning an optional line-break (very useful in poetry, etc).
To make both of the slashes printable, the easiest way is to put a zero-width space between them, either with unicode char 200B (which should be accepted by everything), or if this is the PTXprint-specific front matter, you can use https:/\ZWSP /my.website.org/ Which is a ugly, but when you’re struggling to remember what the trick was in 18 months’ time, it will be save a lot of “But I can’t see any difference!”
