| COMARC/B | December | 2020 |
| 500 | Uniform title |
| 501 | Collective uniform title |
| 503 | Form subheading* |
| 510 | Parallel title proper |
| 512 | Cover title |
| 513 | Added title-page title |
| 514 | Caption title |
| 515 | Running title |
| 516 | Spine title |
| 517 | Other variant titles |
| 518 | Title in standard modern spelling |
| 520 | Former title |
| 530 | Key title |
| 531 | Abbreviated key title |
| 532 | Expanded title |
| 539 | Title proper with LaTeX commands* |
| 540 | Additional title supplied by cataloguer |
| 541 | Translated title supplied by cataloguer |
This block is used for entering data about titles other than the title proper related to the item being catalogued and generally appearing on the item.
In many fields of the block 5XX the indicator 1 distinguishes significant titles. The value "1" in these fields signifies that an added entry with the corresponding heading will be created. Selecting the value of indicator 1 is only important in systems in which they create catalogue slips.