Nested ``++CASxx++``, ``++DO++``, ``++DOU++``, ``++DOW++``, ``++DOUxx++``, ``++DOWxx++``, ``++FOR++``, ``++IF++``, ``++IFxx++``, ``++MONITOR++`` and ``++SELECT++`` statements is a key ingredient for making what's known as "Spaghetti code".

Such code is hard to read, refactor and therefore maintain.

== Noncompliant Code Example

With the default threshold of 3:

----
IF        A <> B
IF        B <> C
DOW       B <> A
IF        A <> D
...
ENDIF
ENDDO
ENDIF
ENDIF
----

----
if a <> b;
  if b <> c;
    dow b <> a;
      if a <> d;
        ...
      endif;
    enddo;
  endif;
endif;
----
