Quad FIO[56] fails writing apl chars

[Hans-Peter Sorge]

Hi,

⍝ This writes apl chars
      some_apl_chars ← '¨¯⍒⍋⌽⍉⊖≠∨∧\⌹@⍵∊⍴t↑↓⍳○p←~'
      fh←'w' ⎕FIO[3] 'XXXX'
      some_apl_chars ⎕FIO[43] fh
60
      ⎕FIO[4] fh
0

⍝ This returns them:
      ⎕FIO[49] 'XXXX'
 ¨¯⍒⍋⌽⍉⊖≠∨∧\⌹@⍵∊⍴t↑↓⍳○p←~


⍝ I did not notice so far that ⎕FIO[56] fails in writing APL characters:
⍝ Is this a bug or am I missing some Docu?
      (⊂ some_apl_chars) ⎕FIO[56] 'XXXX'
25

      ⎕FIO[49] 'XXXX'
 􀂨􀂯RK=I􀂖`('\9@u tt􀂑􀂓s􀃋p􀂐~


Best Regards
Hans-Peter