Rules

• A rule has the format
  if Boolean-Expr then Stmt
• if and then are keywords
• Expr and Stmt refer to expression and statement. They refer to programming language concepts, that I'm not going to fully explain.
• A simplified version is that an expression has a value and a statement does something.
• The if is itself a statement, though it recursively uses statement.
• You can also have compound expressions combined using And Or, or Not
• For example (a > 1) And (a < 10). In Clips
  (value ?a)(test (> ?a 1))(test (< ?a 10))
  which is the same as
  (and(value ?a)(test (> ?a 1))(test (< ?a 10)))
• This stuff is the same for many programming languages, so it should not be new to you.