Occasionally, you may need to interact with a system that cannot cope with the absence of trailing composite delimiters in a particular field. Leaving off the trailing delimiters is actually perfectly legal in HL7, but some legacy systems may be incorrectly programmed and may still require them.

One good example of this problem is a system that might require a trailing caret for a patient's middle initial, even though the patient does not have a middle initial. For example,

|Smith^John^|

is required instead of

|Smith^John|

To handle this problem, add the following code to the segment outbound script for the PID Patient Name field:

# If the second subfield has no content, set it to
# an empty string to ensure the message generator outputs
# a trailing subfield delimiter.
if field.subfield(2).is_null():
   field.subfield(2).value = ''

Another example: some systems may require a fixed number of fields in a particular segment. If you need to generate a segment with a fixed number of fields, you must create a segment outbound script for the last of the fields that needs to appear.

For example, if your segment needs to contain 15 fields, add this code to the segment outbound script for the 15th field:

if value == None:
	value = ''