Approval Procedure for Change Requests/Orders 
The procedure for approving and releasing engineering change requests / orders is controlled via links between statuses and business transactions. The statuses mark particular processing statuses during the approval procedure. They include:
You can proceed from one status to the next by carrying out a business transaction.
See also:
SAP Library LO - Engineering Change Management
System Status
SAP has defined a standard approval procedure, which has been implemented via a network of system statuses. If approval can be granted without difficulties, this procedure could look as follows
Now you can make the planned changes, that is, the master recipe can be edited with reference to the engineering change order.
The recipe has now been approved. It can be used to create orders requiring an approved recipe.

If you want to use more than just the system statuses defined in the engineering change order in your approval procedure, you can use a
User Status
If the approval procedure defined by SAP does not meet all your requirements, you can add company-specific checks at the change order header or change object level. To do so, you assign a change type with a corresponding status profile to the engineering change request or the change objects.
Status profiles are defined and assigned to change types within Customizing for Engineering Change Management. In the status profile, you link the user statuses to the business transactions defined in the standard system. The user statuses are thus inserted in the existing network of system statuses.
You can specify that a special authorization is required to set or delete a user status.