pack bits (!= NULL bits!): One bit per packable column: FIELD_BLOB: Set if blob is empty. No blob data in record. FIELD_SKIP_ZERO: Set if all bytes zero, no data in record. FIELD_SKIP_ENDSPACE, FIELD_SKIP_PRESPACE: Set if some blanks stripped in record. => The "pack bits" are rounded up to the next byte boundary.
Record contents from the in-memory representation. Each field is copied verbatim unless packed according to the "pack bits" paragraph.