Purpose
 
               		 
               		
               For zFS TYPE(U) files only, returns the number of storage units actually written after attempting to write 
                  		  z storage units (bytes) from file 
                  		  x into location 
                  		  y. 
                  		
               
 
               	 
              
            	 
             
            	 
            
               Parameters
 
               		 
               		
                
                  		   
                  			 
                  - x 
                     			 
                  
- File reference. 
                     			 
                  
- y 
                     			 
                  
- POINTER- or OFFSET-type expression. For the OFFSET type, the expression must be an OFFSET variable declared with the AREA
                     attribute. 
                     			 
                  
- z 
                     			 
                  
- Computational-type expression converted to type size_t.