Function  56h   Rename a File 
entry   AH      56h 
	DS:DX   pointer to ASCIIZ old pathname 
	ES:DI   pointer to ASCIIZ new pathname 
return  CF      clear   successful rename 
		set     AX      error code (2, 3, 5, 11h) 
note 1) Works with files in same drive only 
     2) Global characters not allowed in filename 
     3) The name of a file is its full pathname. The file's full pathname can 
	be changed, while leaving the actual FILENAME.EXT unchanged. Changing 
	the pathname allows the file to be "moved" from subdirectory to 
	subdirectory on a logical drive without actually copying the file. 
     4) DOS 3.x allows renaming of directories 
     5) DOS 2.x only: this function renames file by creating a new directory
	entry with the new name, then marking the old entry deleted
     6) This function does not set the archive attribute which results in incremental backups not
	backing up the file under its new name
 
 

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