What is the refid field used for in a c-clip?

It is used internally to "keep alive" blobs that are written until the parent clip is written. It is of no use or interest to users / applications.

Hey Graham -

Would it be safe to say that this is a unique identifier for each blob?  For instance, if I change the metadata for something like EBR status and execute a clipWrite, that refid doesn't change, I'm assuming because the blob data is unchanged, I simply have two CDF's now.  Does that thinking sound correct?

No, the refid is not an identififer for any blob within the clip. Remember that there can be multiple blobs within a clip but there is only one refid. The unique identifier for each blob is contained as a hidden attribute on the blob tag - theses can be seen if you view the raw clip using JCASScript.

As I said, the refid is a temporary CentraStar object that is associated with the blobs of a new clip that is being created. It is used to keep these blobs alive until the final clip is written. Once the clip is persisted it is effectively no longer used. It is of no use to the any application and should be ignored.

Thanks Graham, the rawview was exactly what I needed for my problem and I had forgetten about it.  I appreciate your time and thoughts!!