CAT3 (Time Sheet: Display Times) is a standard SAP transaction code available within R/3 SAP systems depending on your version and release level. 

Below for your convenience is a few details about this tcode including any standard documentation available. In-order to use this transaction within your SAP system simply enter it into the command input box located in the top left hand corner and press enter. Here are a few additional command options available to use when doing this. 

GUI Support 
 SAPGUI for HTML
The SAP GUI for HTML generates HTML pages for every SAP screen. This means that you do not have to create any templates. There are however some technical restrictions due to the browser and certain transactions may not function in the SAP GUI for HTML. 

 SAPGUI for Java
SAP GUI for Java is a plug-in, a program downloaded from the browser to the PC and executed there. This GUI version supports more controls than the SAP GUI for HTML, but you should still test the transaction. It also requires users to download and install the client on their PC so the Java GUI is the second choice after the SAP GUI for HTML. 

 SAPGUI for windows
Transactions can also be run under SAP GUI for Windows. It must be flagged with SAPgui for Windows (previously known as WinGUI).

SAP Menu->Logistics->Sales and Distribution->Sales->Product Cost by Sales Order->Actual Postings->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Logistics->Plant Maintenance->Maintenance Processing->Completion Confirmation->Entry->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Logistics->Customer Service->Service Processing->Confirmation->Entry->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Logistics->Project System->Progress->Confirmation->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Accounting->Controlling->Cost Center Accounting->Actual Postings->Time sheet->CATS Classic->Display Working Times 

SAP Menu->Accounting->Controlling->Internal Orders->Actual Postings->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Accounting->Controlling->Activity-Based Costing->Actual Postings->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Accounting->Investment Management->Internal Orders->Actual Postings->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Accounting->Investment Management->Investment Projects->Actual Postings->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Accounting->Project System->Progress->Confirmation->Time Sheet->CATS Classic->Display Working Times 

SAP Menu->Human Resources->Time Management->Time Sheet->CATS Classic->Display Working Times