Final answer:
An X in Block 8 of the CMS-1500 claims form means the claim contains a Medicare Part A service, which covers hospital expenses and has no cap on patient costs.
Step-by-step explanation:
An X in Block 8 of the CMS-1500 claims form indicates that the claim contains a Medicare Part A service. Medicare Part A primarily covers hospital expenses, funded through payroll deductions and employer contributions. Beneficiaries must meet deductible charges and may also have copayments for hospital services, and it is important to note that there are no caps on the total costs that may be incurred by the patient.