Final answer:
To define a new time card field, refer to the specific software's documentation or customer support for a list of valid data sources such as employee information, project codes, or payroll details.
Step-by-step explanation:
The list of valid data sources for defining a new time card field in a system very much depends on the specific timekeeping or workforce management software being used. Generally, a time card system may allow for a variety of data sources including employee information, project codes, or payroll details. It's crucial to refer to the documentation of the specific software or to contact their customer support for the complete list of valid data sources.