Custom data fields can capture and display additional information.
Core HR > Account data > Custom data fields
Add flexible custom data to shifts, roles, locations, earning rates and leave types. Custom data can be numeric, text, an option list, or even a file.
Types of custom data
Custom shift data is one of the most commonly used types. It can be used for creating notes that can be sent to employees, adding cost codes, identifying shifts where employees work higher duties, tagging shifts using text and colour.
If multiple custom data fields are added to shifts, they will display alphabetically. Control the display order on the shift by using numbers as field name prefix – 00 Supervisor, 01 Uniform, 06 Cost Centre etc. 
Another example could be creating a custom data field for 'Location type', for example 'Indoor' or 'Outdoor'. This can then be added to locations via the Core HR > Organisation Structure > Locations page. This is not something that would display on a roster, but may be used as a condition in awards or for reporting. 
Reporting
One of the benefits of using custom data fields is that they can be used extensively for reporting.
Creating a Location type custom data field like above will automatically create a Location - Location type report that can be run from the Rostering > Reports menu, like the Earning rate - Loading type report that can be run from the Payroll & leave > Reports menu.
Custom shift data can be added to Custom Shift Export templates, and custom shift reports can be run from the timesheet review, schedules, shift history and pay cycles pages.
Custom employee data is different to other custom data, it is created and stored as Objects and Object Groups, which display as tabs on employee profiles, and can be added to Custom Employee Export templates, and run from Core HR > People > Employees.
Read up on using Custom export templates here.
Where to now?
Other related articles
Using custom data fields as shift notes
Custom export templates