UKMARC to MARC21: most used fields
| 021 | 020 | ISBN |
| 021 | 022 | ISSN |
| 022 | 022 | ISSN |
| 040 | 040 | Cataloguing source |
| 041 | 041 | Trans. codes |
| 082 | 082 | Sugg. Dewey no. |
| 100 | 100 | Author (Personnel) |
| 110 | 110 | Author (Corporate) |
| 111 | 111 | Author (Conf.) |
| 200 | 209 | DONs/SOs |
| 240 | 130 | Uniform main |
| 240 | 240 | Uniform not main |
| 240*z | 245 | Uniform GMD |
| 243 | 240 | Collective title |
| 245 | 245 | Title |
| 245 | 130/240 | Serial with *C |
| 245*k | 245&246 | Parallel title |
| 245*i&j | 245&740 | 2nd & subseq. title |
| 246 | 246 | Varying titles - Serial |
| 248 | 245 | Multi-parts |
| 248*h,i,j,k | 245&740 | Part titles |
| 250 | 250 | Edition |
| 260 | 260 | Publication |
| 300 | 300 | Pagination |
| 300*e | 020 | Binding state. |
| 440 | 440 | Series - no b,k,e |
| 440 | 490 | Series - b,k,e |
| 440 | 830 | Series - b,k,e |
| 490 | 490 | Series |
| 500 | 500 | Note |
| 502 | 502 | Dissertation note |
| 503 | 500 | Edition-Mono |
| 503 | 580 | Edition-Serial |
| 504 | 500 | Index note only |
| 504 | 504 | Bibliography (with/out index) |
| 505 | 505 | Contents |
| 506 | 511 | Performer |
| 508 | 500 | State. of resp. |
| 514 | 500 | Title information |
| 515 | 500 | Seq. design.-serial |
| 525 | 500 | Accomp. mat. |
| 528 | 500 | Public. notes |
| 542 | 538 | Mode of use (computer files) |
| 546 | 546 | Lang. note |
| 550 | 550 | Issuing body note |
| 580 | 580 | Linking entry |
| 600 | 600 | Subject-Personal |
| 610 | 610 | Subject-Corporate |
| 611 | 611 | Subject-Conf. |
| 640 | 630 | Uniform title |
| 650 | 650 | Topical subject |
| 651 | 651 | Geographic subject |
| 700 | 700 | Added-Personal |
| 710 | 710 | Added-Corporate |
| 711 | 711 | Added-Conf. |
| 740 | 730 | Added-Uniform title |
| 745 | 246 | Added-Title |
| 760 | 760 | Series link |
| 762 | 762 | Sub-series link |
| 765 | 765 | Orig. lang. entry |
| 767 | 767 | Translation link |
| 770 | 770 | Supplement link |
| 772 | 772 | Parent record link |
| 777 | 773 | Links: 2nd I=1 |
| 777 | 774 | Links: 2nd I=2 |
| 777 | 777 | Links: 2nd I=0 |
| 780 | 780 | Preceding link |
| 785 | 785 | Succ. link |
| 787 | 787 | Non-spec. link |
| 840 | 830 | Added series |
| 856 | 856 | URL |