Hi Andy,

interesting issue. I just tried some other XQuery processors in order
to find out how they resolve the name of a local file:

• File: [].xml
• Query: base-uri(doc('[].xml'))

• Saxon:
  FODC0002: Exception thrown by URIResolver:
  Invalid relative URI {[].xml}: Illegal
  character in path at index 0: [].xml
• Zorba:
  [err:FODC0005]: "[].xml": invalid URI literal: "91": invalid character c
• BaseX:
  [FODC0005] Invalid document URI: '[].xml'.

I have added an issue in the W3 bug tracker [1]; let's wait for the response.

Christian

[1] https://www.w3.org/Bugs/Public/show_bug.cgi?id=27612