13.33.81.2 Description

Auxiliary files are not audited and are handled as one-time data-entry or data-change events, similar to entering data using one of the interactive editors (for example, PinEditor or Timer).
If you import the SDC file as an auxiliary file, you do not have to re-compile your design. However, auditing is disabled when you import auxiliary files, and Designer cannot detect the changes to your SDC file(s) if you import them as auxiliary files.