...
2. Restrict the use of 78x fields to "work-level" changes in the title only, and use 776 fields (Additional Physical Form Entry) exclusively when recording the appearance or existence of a title in another format.
When a title originally issued in one format begins or is discovered to be issued in another format, the cataloger should create a record for the title under its new format, and connect the two with reciprocal 776 fields. First indicator: 0 (display note); second: 8 (no display constant). Add a note in subfield i (Relationship information (R)) to indicate the format of the record that the 776 is targeting. If known, add chronological designations of the span of publication in the targeted record in $d (Place, publisher, and date of publication (NR)).
Example:
{{
1242732
245:00: $a Bulletin of the atomic scientists.
776:08: $i Online version: $t Bulletin of the atomic scientists $x 1938-3282 $w (DLC) 2006238205 $w (OCoLC)37476498
37476498
245:00:$a Bulletin of the atomic scientists electronic resource.
776:08: $i Print version, -2008: $a Bulletin of the atomic scientists $d 1946-2008 $x 0096-3402 $w (DLC) 48034039 $w (OCoLC)1242732
}}
...
3. Use MARC field 787 (Other Relationship Entry) when recording the appearance or existence of a title in another format.