Final answer:
A source document used to assign direct labor costs to individual jobs is known as a time ticket, which records the time an employee spends on specific jobs.
Step-by-step explanation:
A source document by which direct labor costs are assigned to individual jobs is known as a time ticket or job time ticket. This document is a record of the amount of time a worker spends on a specific job or project. The time ticket includes details such as the date, the employee's name, the job identification number, and the number of hours worked. This information is critical for accurate job costing and helps ensure that labor costs are appropriately allocated to jobs for cost tracking and financial reporting.