APPEND is useful but should be used with caution. Many programs do not use 
the PATH environment variable to locate input files. APPEND will allow such 
commands to find their input files even when they are not in the current 
directory. 

WARNING: While use of APPEND will allow commands to find input files, output 
files will still be written in the current directory if an explicit pathname
is not provided. This may not produce the desired result. 

APPEND is typically included in the AUTOEXEC.BAT file. APPEND may be executed 
multiple times to add to its list, but it can only be 127 characters long. A 
long pathname may exceed this limit. Careful use of the SUBST command before 
executing APPEND can alleviate this limitation. If the /E option is used, the 
SHELL line in CONFIG.SYS may be needed to increase the size of the DOS
environment space. 

DIR with wildcards will list files in the current directory and (possibly) 
in APPENDed directories, which can get confusing.
