DUG Insight uses SEG-Y rev 1 headers in its internal data format. This table lists the purpose to which Insight puts those headers, assuming that the data was loaded from field tapes in Insight, and that the header values haven't since been modified. If Insight doesn't use a header for any particular purpose, its SEG-Y rev 1 description is given.

Your data, of course, might have values in these headers that have different meanings.