Hello,
This is a Regular expression pattern(RegEx).
xs:pattern value="([ -~])*"
[ ] is a character class, that means it will match one character out of all the class possibilities.
- means a range of characters, here all characters from " " to "~"
( )is a group
* means as many time as you wish.
So basically it means that you can have any characters between " " and "~" repeated as often as you want. Any other character will make the node invalid.
See details here:
http://www.regular-expressions.info/reference.html[
^]
Valery.