ManageSieve: allowed characters in script names

[Alexey Melnikov <alexey.melnikov@xxxxxxxxx>]

draft-martin-managesieve-08.txt [currently expired], section 1.7 says:

   Sieve script names may contain any valid UTF-8 characters, except
   for NUL, CR or LF. Names MUST be at least one octet long. Zero
   octets script name has special meaning (see SETACTIVE command
   section). Servers MUST allow names of up to 128 Unicode characters
   in length, and MAY allow longer names.

Is this reasonable? I think we should at least prohibit other ASCII 
control characters.

Isode's implementation is even more restrictive, as it disallows ¬, :, 
/, etc. Should they be allowed?