Following another post in the forum I tried to use the frac feature of an OpenType font (Linux Libertine). To easy the handling I'm using prince-text-replace to replace the ordinary slash with the correct fraction slash (\2044, ⁄). But that didn't work. What am I doing wrong?
Forum › How do I...?
Usage of prince-text-replace for fractions with OpenType feature "frac".
Sorry, this one is my fault. 
Prince is adding zero-width space characters after slashes, so that long URLs can break lines instead of overflowing into the page margins. Unfortunately, this is breaking the OpenType features.
You can avoid it by applying "prince-linebreak-magic: none".
We may need to reconsider whether this process should be applied by default, or whether there is another way to do it which won't interfere with OpenType features.
Prince is adding zero-width space characters after slashes, so that long URLs can break lines instead of overflowing into the page margins. Unfortunately, this is breaking the OpenType features.
You can avoid it by applying "prince-linebreak-magic: none".
We may need to reconsider whether this process should be applied by default, or whether there is another way to do it which won't interfere with OpenType features.