Each item automatically receives a unique ID (across all projects) after creation, which consists of the prefix RQ (Requirement), TC (Test Case), TS (Test Scenario), or DF (Defect) and a 6-digit number with leading zeros. The IDs are automatically incremented. If so many elements have been created that the IDs exceed the 6 digits, the IDs are automatically extended by one digit. The same applies if more digits are reached. Thus there is no limit to the length of the ID and therefore no limit to the number of elements (except maybe the size of the database). The formatting cannot be adjusted, i.e. you cannot, for example, remove the prefixes or specify a 7-digit number with an additional leading zero from the beginning.
Please also note that unexpected shutdowns or crashes of the database can cause jumps in the IDs of 1000 digits. This is due to a feature of SQl databases called Identity Cache, which improves performance and has no further effects, and can therefore be ignored.
