I got the first empirical answer:
for /f %%s in (version.txt) do ...
works fine on every computer.
, for /f , - dos, 'type filename'.
( , " " )
15 (?) ;-), :
'for/f' , . DOS?
: 3 (!), barlop , "for /f cmd?". :
COMSPEC SET + ENTER.
, , COMSPEC . System Variables, , , .
ss64, Andriy M , .
< <26 > 'dir' ( , ) COMSPEC, cmd.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\ComSpec=
%SystemRoot%\system32\cmd.exe