Approval via SAP Business Workflow 
Use
The workflow scenarios in Travel Management strongly support the decentralized trip facts entry model. The advantage is that they connect all persons who are involved in approval directly via the R/3 System, making the approval processes much more efficient.
Prerequisites
You have to have set up SAP Business Workflow and the Travel Management workflow scenarios.
Features
The approval of employee trips can be carried out in SAP Business Workflow via two different reference approval procedures. On the one hand there is the one-step approval process for requests and, on the other, the two-step approval process for trips.
The One-Step Reference Approval Process for Requests
The Two-Step Reference Approval Process for Trips
See also:
For further information on SAP Business Workflow in general and on the Travel Management workflow scenarios, see the documentation on SAP Business Workflow.
You will find the documentation for Travel Management under:
Workflow Scenarios in Travel Management (FI-TV)
Technical Background (FI-TV)
Preparation and Customizing (FI-TV)
Using and Linking to Application Functions (FI-TV)