When you save a message definition file, the definitions that it contains are checked to ensure that they make sense and provide sufficient information about the message. This action is called validation.
The CWF physical format depends on fixed format data structures, so the majority of tests applied to a CWF message confirm that each fragment of a message (and therefore the message as a whole) has a well defined length. Thus, these tests examine properties such as Length Count, Length Reference and Length Units.
Typically, one or other of Length Count and Length Reference must be set. If Length Reference is set, then it must refer to an element that is of simple type integer and that appears earlier in the message than the current item.
Tests other than these tend to be both simple and obvious so that, for example, the message set property First Day of Week has to be the name of a day in the week.
The fact that CWF relies on fixed format data structures also imposes some limitations on the messages that can be represented: