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.
TLD = Top-Level Domain. In a URL, the part right after the protocol (usually http or https) is the host name: for example, wiki.answers.com. The last part of that is the top-level domain, in this case .com.