Editing Systems 
Once you have created a system, you may need to edit it through the System Landscape Editor. To edit a system is to assign values to its properties, such as the specific properties that enable connection to an external application.
The portal installation contains system templates for systems connecting to JDBC and SAP applications.
Once the system properties are stored in the Portal Content Directory (PCD), they serve as a definition of the system and the connector to which they relate.
Certain properties in these files are mandatory and common to both templates, while other properties are dependent upon the particular application to which you are connecting.
To enable connectivity to a particular application, the property values and attributes of the system to which you are connecting must have values corresponding to a description of that application.
Some property values are mandatory and cannot be changed.
Other properties need to be provided with the correct values before connectivity to the external application can be established.
The two properties demanded by the System Landscape service, com.sap.portal.pcm.Title and ComponentType ,are part of each template that you upload.
A third property, com.sap.portal.reserved.system.ConnectionFactoryClass, is mandatory only if you are working through a connector.
An additional property that may appear, com.sap.portal.reserved.system.ConnectionGroup, specifies the group of properties used or needed to connect to the system. It is an optional property that currently is relevant only for R3 systems.
It is possible to edit properties and attributes by overriding existing values, but existing properties cannot be added or deleted.
In the property list, enter values for those properties the values of which are not set and which need values, using the guidelines provided for each system:
Editing property attributes:
In the Property Editor, click the arrow beside any particular property to view and edit property attributes
Click Save to effect any changes.
Defining user mapping (for establishing a JDBC connection); see Accessing Back-End Systems with a Different User ID and System Properties for User Mapping.
Defining a default system alias; see System Aliases.
Testing the connection to the back-end application represented by the system; see Testing System Connections.