A semicolon (;) should be used to end each and every SAS statement. Additional semicolons (;) can normally be used between any two SAS statements anywhere in SAS code without ill effects. However, there are two situations where a semicolon should be used with care.
After a DATALINES4 statement, four semicolons in a row (;;;;), and starting on a new line, are needed to end a group of datalines that might contain semicolons.
Other than that, additional semicolons between statements are treated as null statements that convey no additional meanings to SAS.