A more thorough explanation:

The human-leukocyte antigen test is a medical procedure that involves analyzing a man's blood sample in a paternity or legitimacy case. This is done by comparing certain indicators in the man's blood with those in the child's blood. The test is abbreviated as HLA test and is often used in conjunction with blood-grouping tests and genetic-marker tests.

For example, if a woman has a child and is unsure who the father is, she can request an HLA test to determine paternity. The test will compare the HLA markers in the child's blood with those in the potential father's blood to see if there is a match. If there is a match, it is likely that the man is the biological father of the child.

Another example is in organ transplantation. The HLA test is used to match the donor's and recipient's HLA markers to ensure that the organ is not rejected by the recipient's immune system.

These examples illustrate how the HLA test is used to determine biological relationships and compatibility in medical procedures.