讀出功能模組文件 SAP Function Module Documentation

Get SAP function module documentation

Step 1 - Execute transaction SE37 
First, execute sap transaction SE37 and enter the function module name. Then press the display button 
 

Alternatively, choose menu option Goto->Documentation->Function Module Documentation. The only problem I find with this option is that the documentation popup box appears underneath the current SAP window so you don't actually see it without moving the window 
 

Step 2 - Display documentation 
If you selected display you will be taken to the FM details, now simply choose the menu option goto->Documentation. 
 

The Function module documentation will now be displayed 
 

Step 3 - Alternate way using tcodevSE80 
You also get the same options to view Function Module documentation within SAP transaction SE80