Warning: submitter emailed me:
Gdańsk 80-855
Wały piastowskie 1/1508
od -c 
0000000    G   d   a   &   n   a   c   u   t   e   ;   s   k       8   0
0000020    -   8   5   5  \n   W   a   &   l   s   t   r   o   k   ;   y
0000040        p   i   a   s   t   o   w   s   k   i   e       1   /   1
0000060    5   0   8  \n                                                
xd
----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
Gdańsk 80-855?
466266677637623323330
7416E13545B3B080D855A
----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
Wały piastowskie 1/1508?
5626777663727667767766623233330
716C342FBB9009134F73B9501F1508A
----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
tidy -i -m then corrupts it to
Gdańsk 80-855
Wały piastowskie 1/1508
which Czcibor says is wrong
So I suppose tidy is not recognising ń
though tidy does recognise eg *uuml; from u umlaut in Muenchen = Munich
Maybe I need a newer vrsion of tidy ?
Or maybe Czcibor might need to inform tidy author to add a new escape sequence.
I note my entire web space has no other usage of nacute
Ive no time to investigate more at present