can some definitively explain these? i've read over many of the old posts and can accomplish what i need to do, but am not *crystal* clear on this. thanks alot. -a -- ==================================== | Ara Howard | NOAA Forecast Systems Laboratory | Information and Technology Services | Data Systems Group | R/FST 325 Broadway | Boulder, CO 80305-3328 | Email: ahoward / fsl.noaa.gov | Phone: 303-497-7238 | Fax: 303-497-7259 ====================================