Figured it out.  I wasn't "naming" my span correctly.  Once I got an ID for the span, I can choose that ID for my Partial Update.

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Is it possible to do a Partial Update on a span?  I have several fields that I am doing a Full Update in the onchange event, but that refreshes the entire page, and I lose focus on the field I'm in.

I'd like to do a partial refresh on two images for each required field, so the user can see when each required field is completed.