ie. You can own the surface rights, but you sell the timber rights to farmer John for 25 years. The nature of the status of the land is fixed by law, and are distinguished as being either a freehold estate or a non-freehold estate. Freehold means ownership without limitations to duration.
The acronym PDF stands for 'Portable Document Format'. This long form of the acronym still doesn't tell you a lot, but it can give you a rough idea of what we are talking about. One thing that you can grasp easily is that it's a 'Document Format'.
Invented by Adobe, PDF is now an open standard maintained by the International Organization for Standardization (ISO). PDFs can contain links and buttons, form fields, audio, video, and business logic. They can also be signed electronically and are easily viewed using free Acrobat Reader DC software. We invented PDF. In 1991, Adobe cofounder Dr. John Warnock launched the paper-to-digital revolution with an idea he called The Camelot Project.