I am a German, born 1965 in Dortmund. I did learn to read the old German characters in use until the 1st half of 20th century, but not to write them.

Today my attention was brought to this again by this tweet (pointing to a nice code piece):
https://twitter.com/pilif/status/535065994843406336

First I learned from Wikipedia that the black-letter characters were in use in Germany from 1150 until 1st half of 20th centurty:
http://en.wikipedia.org/wiki/Blackletter
http://en.wikipedia.org/wiki/Blackletter#Unicode

And that similar letters for use in mathematical formulas are called fraktur.

Then I wanted to see how much black-letter will be allowed in XSLT, and therefore started with  hello-world.xsl .

It just outputs "Hallo Welt!" which is German for "Hello world!":

Next I wanted to replace all ASCII characters in that stylesheet by their black-letter counterparts.

The string of all black-letter characters was given under above "...#unicode" Wikipedia link, and XPath translate() function𝖊𝖓𝖈𝖔𝖉𝖎𝖓𝖌 did the rest:

translate(
  .,
  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz',
  '𝕬𝕭𝕮𝕯𝕰𝕱𝕲𝕳𝕴𝕵𝕶𝕷𝕸𝕹𝕺𝕻𝕼𝕽𝕾𝕿𝖀𝖁𝖂𝖃𝖄𝖅𝖆𝖇𝖈𝖉𝖊𝖋𝖌𝖍𝖎𝖏𝖐𝖑𝖒𝖓𝖔𝖕𝖖𝖗𝖘𝖙𝖚𝖛𝖜𝖝𝖞𝖟'
)

Not surprisingly the stylesheet did not compile, it missed "version", "encoding" and other stuff required by XSLT 1.0 spec and did not know what "𝖛𝖊𝖗𝖘𝖎𝖔𝖓" and "𝖊𝖓𝖈𝖔𝖉𝖎𝖓𝖌" should be. So I repeated compile-fix until the stylesheet finally compiled again. This is the result -- vi's syntax highlighting does not like black-letter ;-)

Here you can see it work:

Hermann _{<myBlog/> <myTweets/> | <GraphvizFiddle/> | <xqib/> | <myCE/> <myFrameless/> |}