ON Blocks

You've seen that every rule is made up of ON blocks. There are two main types of ON blocks:

• blocks that process an external data source, extracting information, and
• blocks that work on internal data, such as variables

As Figure 105 illustrates, there are several types of external data sources:

Figure 105 ON Block Structure Summary

In Figure 106, the two types of data sources (ON SYSOUT and ON FILE) that were used in solving the six problems described in this chapter are checked.

While the other three types of data sources (ON CLASS, ON DDNAME, and ON DSN) would require different ON specifications, the rule definitions that would use these data sources would be nearly identical to those using ON SYSOUT and ON FILE.

Figure 106 Data Sources That ON Statements Can Process