Using Pipes

The number of PIPEs (|) in one OS/2 command is limited to n, where n 
depends on the length of the current value of the <PATH variable. To get 
around this limitation, group together parts of your command in 
parentheses. 
Example: Instead of 

 
  a | b | c | d | e | f

use 

 
  (a | b | c) | (d | e | f)

(where a, b, c, d, e and f are OS/2 commands or programs). The parts in 
parentheses are executed by separate CMD processes and no CMD process must 
create more than 2 PIPEs.   

Source:  c't 1/1996 

  (see also Pipes & Errorlevel)