The function DIRECTORY()

If you use the function <DIRECTORY on a drive which isn't ready, OS/2 
always pops up this nice little error box. There's no way to avoid this 
(No, even an active trap for NOTREADY conditions will do that). 

For a workaround for this behavior see Check if a directory exists 

Note:  The DLL RXU contains a function to enable and disable popups for 
       hard errors and exceptions. 

 In OS/2 WARP the function <DIRECTORY fails if the name of the directory 
 is too long (more than 132 chars). This bug is fixed in the WARP 3 
 FixPack (Source: APAR PJ19343).