It's tough when looking at the C32 spec to tell whether `<effectiveTime>`s are supposed to be a range or a single date. Can anyone clarify for sure what type of `<effectiveTime` labs are supposed to use?

FWIW the [C32 spec for lab results](http://cdatools.org/infocenter/index.jsp?topic=%2Forg.openhealthtools.mdht.uml.cda.hitsp.doc%2Fclasses%2FResult.html) (not labs) seems to say `<effectiveTime>` should be a single date, but I've seen both single dates and ranges in sample files.