To add new include files to the project: 
	 
 
	  
		- Right-click the project in Solution Explorer. 
		
- Click 
		  Add > 
		  New Item. 
		
- In the 
		  Installed Templates pane, click 
		  PL/I Items, and click 
		  PL/I Include. 
		  The default name of the file is 
			 Include1.inc.
		   
- Click 
		  Add. 
		  Note: When an include file is added in this way, its build action is set to 
			  "None". To see this, click the file in Solution Explorer and check the 
			  Properties window to notice the value of the 
			  Build Action option.
		   
 
To add existing include files: 
	 
 
	  
		- Go to the project's properties, and open the 
		  Dependency Paths tab. 
		
- Put the directory where the include files are under 
		  PL/I Include Paths. 
		
- Right-click the project in Solution Explorer. 
		
- Click 
		  Add > 
		  Existing Item and browse to the location of the include file. 
		
- Select the include file you want to add to the project. 
		
- Click 
		  Add. 
		
Note: You need to add the include files to the project so that the build process will recognize when an include file has changed and will recompile the appropriate programs. It will also help with features such as find in files.