case the literal text case (case insensitive) \s+any whitespace character, repeated at least once
when the literal text when (case insensitive) \s+any whitespace character, repeated at least once
(?&clause)calls group clause as a subroutine
\s+any whitespace character, repeated at least once
then the literal text then (case insensitive) \s+any whitespace character, repeated at least once
(?&expr)calls group expr as a subroutine
\s+any whitespace character, repeated at least once
else the literal text else (case insensitive) \s+any whitespace character, repeated at least once
(?&expr)calls group expr as a subroutine
\s+any whitespace character, repeated at least once
endthe literal text end (case insensitive)