In segments, it is important to note that there is a difference between fields that have no value defined for them and fields that have a null value defined for them.
If a field is not defined, there is nothing between the two | characters that delimit the field:
OBR|||||||||
A null value is indicated by two double-quote characters:
OBR|||||””||||
A field for which a null value has been defined is often referred to as present but null. Present but null fields are used in many applications.
