ist or be selected individually. For template tasks, values are assigned for the place holders when the data source is configured. Data sources are created by assigning a set of values to the place hold- ers in the task template. Only one data source can be associated at the time of exe- cution of a template. Existing data sources are displayed in the task execution wizard. Wizards improve usability, especially for first-time users, but are not pro- vided in all current OSS software. The data sources are displayed in the left column of the screen and each data source's defined place holder on the right side of the screen. Values for configured place holders can be entered as data source param- eters in a screen such as that in Figure 11.25. oss for Telecom Networks Execute Task Execute Task A Configure Data Source Parameters Configure Data Source Paramters eDelete serinput Value Password Password incominginterface outgoingInterface listno listno Value Update rameters Cancel Cancel Figure 11.25 Configuring data source parameters. 11.2.15.4 Executing Combined Tasks When two or more configured tasks, possibly based on different protocols, are to be executed at a particular time, then they can be combined together to form "com- bined tasks". Every configured task which is listed as a sub-task under a combined task can be executed on separate devices. There is a wizard for executing combined tasks (see Figure 11.26). As seen in Figure 11.26, the sub-tasks that are present in a combined task are dis- played under their respective protocols in the tree. 11.3 Configuration Management Implementation We now turn to configuration management as implemented by Clarity's Configuration Manager product. Clarity Configuration Manager (CCM) manages telephone number creation and allocation, in addition to supporting the logical and physical configuration of telecommunication networks. The product integrates NEs and network element management systems (NEMSs). With appropriate interfaces, the product can communicate with other suppor