You can nest conditional action statements to any number of levels; that is, you can specify conditions within other conditions. Note that you must specify the end if keywords corresponding to each if test; for example:

 

if (TestSuccessFlag) then

    if (A > B) then

        copy A to K

        send A_Msg to Recorder

    else

        send B_Msg to Recorder

    end if

end if

copy A to Log

 

ESL initially evaluates the boolean in the first if statement. If the value of the TestSuccessFlag variable is true, ESL executes the then clause. The first action statement in the then clause is another if statement:

 

if (A > B) then

 

ESL evaluates this boolean. If A is greater than B, ESL executes the then clause:

 

copy A to K

send A_Msg to Recorder

 

ESL ignores the else clause and continues execution at the statement following the second end if:

 

copy A to Log

 

If A is not greater than B, ESL executes the else clause:

 

send B_Msg to Recorder

 

ESL ignores the then clause and continues execution at the statement following the second end if:

 

copy A to Log

 

If the value of the TestSuccessFlag variable is false, the result of the first boolean is false, and ESL ignores the entire outer then clause. Because there is no else clause corresponding to this condition, ESL continues execution at the statement following the second end if:

 

copy A to Log