DESCRIPTION 
This function returns the difference in days between the date of the
DIFF_DATE(1,8)>5
This will be true if the dates of finding 1 and finding 8 are more
than 5 days apart.
DIFF_DATE(1,8,"N")<6
This will be true if the dates of finding 1 and finding 8 are more
than 6 days apart and the date of finding 8 is after finding 1.
Immunization findings can have associated contraindications and refusals.
To use them in the DIFF_DATE function, precede the finding number with a
first finding in the list and the date of the second finding. The
'C' or 'R'. For example, if finding 1 is an immunization and we want to
determine if there are more than 20 days between a contraindication and a
refusal the function string is:
DIFF_DATE(C1,R1)>20
default is to return the absolute value, but if the optional third
parameter of "N" is present, then the actual value is returned. If
you use the actual value, be aware that if the second date is more
recent than the first, the result will be negative.
Some examples:
