The design, development and documentation of software. See software engineer, systems analysis & design, programming, object-oriented programming, software metrics, CASE and Systemantics.
Overview. Posttransplant lymphoproliferative disease (PTLD) is an unusual entity that has many features of an immune system malignancy. It is characterized by uncontrolled proliferation of lymphoid lineage cells (typically B cells, rarely non-B lineage) in a context of posttransplant immunosuppression.
In a small percentage of cases, these symptoms can last for more than 6 months. Although sometimes called chronic Lyme disease, this condition is properly known as  Post-treatment Lyme Disease Syndrome  (PTLDS).