If you can use XSLT 2.0, then you can convert the strings into
dates and compare them with the built-in functions.
You could also use the EXSLT functions (Google for EXSLT date and
whatever processor you are using).
Third, you could call out to a Java extension function. With Stylus
Studio, there is an example included that calls into a date-related
method that you could use as a basis for your code.
I did a draw_date - sysdate in the sql. This gives me a value and I did a "if diff < 7 " in xslt.
Worked out much simpler and cleaner in my code.
Thanks