NDR checklist: CDLXX

The current NDR checklist says:

   [CDLXX] The tokens comprising the URN MUST adhere to the
   following guidelines

    - Whitespace MUST NOT be used within the URN.

    - Special characters MUST NOT be used within the URN. Special
      characters are those characters outside of the range 0-9 or
      a-z.

    - lowercase letters

    - If the code list version identifies a minor version then the
      major and minor version of the code list MUST be separated
      by a period (.).

The third bullet seems a bit terse.  Is it supposed to say that
only lowercase letters should appear in the URN?

Jon