What follows is a table of possible differences between records, arranged by MARC tag number. The first column of the table lists common differences between records; the second column specifies whether that situation prevents you from merging the records.
To use the table, assume you can merge the records unless the tables say otherwise. Identify the differences between records, and look them up on the table.
Red indicates that the difference is one that strongly indicates the records should not be merged.
Blue indicates that the difference is not significant: if all differences are blue, that strongly indicates the records can be merged.
Red v. Blue is not a democratic election! Red trumps blue, and you should be extremely cautious of merging two records with even a single red "look for other differences."
Black indicates that the difference may or may not be significant. Proceed with caution.
| 001 : OCLC Record Number | ||
| Different numbers: merged on OCLC | Merge | |
| Different numbers: not merged on OCLC | Look for other differences | |
| 010 : LC Card Number | ||
| One number in subfield |z | Look for other differences | |
| 020 : ISBN | ||
| Different ISBN numbers | Look for other differences | |
| One record lacks ISBN | Look for other differences | |
| 245 : Title & Statement of Responsibility | ||
| Differences in subfield |a that cannot be attributed to typographical errors or choice of title/subtitle | Do not merge | |
| Typographical errors | Look for other differences | |
| Differences in punctuating 245 | Look for other differences | |
| Subfield |b of one record is included in subfield |a of the other record | Look for other differences | |
| One record lacks subtitle | Look for other differences | |
| Pre-1973 record lacks subfield |c | Look for other differences | |
| 260 : Publication | ||
| Different place of publication | Look for other differences | |
| Different publisher | Do not merge | |
| Abbreviated vs. full version of publisher's name | Look for other differences | |
| Same date: One record lacks "c" in front of date | Look for other differences | |
| Same date: One record brackets date | Look for other differences | |
| Different date: printing date | Look for other differences | |
| Different date: publication date | Do not merge | |
| 300 : Physical description | ||
| One record lacks preliminary or post paging | Look for other differences | |
| Difference in pagination | Look for other differences | |
| One record indicates illustrations | Look for other differences | |
| Difference in size | Look for other differences | |
| 4XX : Series | ||
| One record lacks series | Look for other differences | |
| Different series | Look for other differences | |