[idn] another question about IDN label length

[Soobok Lee <lsb@postel.co.kr>]

 L1 is a utf8-encoded IDN label.

 L2=nameprep(L1), L2 is still in utf8.

 A1=ToASCII(L2)

 Function length(X) returns the octet length of the string X
 in unknown encoding and charset.

 My question in previous questions was:
   in the case of  length(A1)<=63 and length(L2)>63,
    is  L2  a valid iDN label conforming to DNS label length
     restrictions ?


 My second question is:

   if length(L2) <= 63 < length(L1),
     is L1 is valid iDN label ?

   if length(L1) <= 63 < length(L2),
     is L2 is valid iDN label ?

 I can repeat similar questions  by changing utf8 to
   other charset encodings, which will further complicate
   the problem.

 Some applications may exchange non-ASCII-form IDN instead 
 of ACE-form IDN  after negotiations. Non-ASCII-form IDN
 may be used and stored and transfered and processed as 
 its equivalent ACE version  by the new application protocols.

 If some of above labels should be declared as invalid,
  there may be needed more complex definitions of
   what labels are invalid and therefore related protocol actions
   and exception handlings of such too-long IDN labels.

 This problem has security implications from the implementors'
 viewpoints.
 
 If IDNA  draft already
 contains any clues about  iDN label length restrictions,
 suggest me the section please, so that i remain comfortable with
 this issue.


 Regards,

Soobok Lee