What's the effect of using a semi-colon at the end of a DATA step?

Using a semicolon at the end of a DATA step is significant in SAS programming as it marks the conclusion of the DATA step. This tells the SAS language that the statements you have written for that particular DATA step are complete and that SAS can proceed with processing them. Each step in SAS, whether it be a DATA step or a PROC step, requires a semicolon at the end to delineate where that step finishes.

When a semicolon is placed at the end, SAS knows to execute the entire block of code associated with the DATA step. If the semicolon is omitted, SAS may not interpret the statements correctly, leading to potential errors or unexpected behavior in the execution of the program. This illustrates why clarity and precision in syntax are essential when writing code.

In contrast, the other choices do not accurately reflect the role of the semicolon in a DATA step. While it’s true that semicolons are syntactically significant, suggesting they cause errors or are optional misrepresents their critical function in the SAS programming structure.