I consider OCR PDF or OCR Document I think of a desktop software program and allows you to convert documents into searchable or editable text if your PDF application or other document software cannot do this.
It is also used in Scanners or fax machines (more often scanners) where documents which are scanned to PDFs or other documents are automatically made searchable or editable by the use of the OCR.
OCR also allows PDF to be marked up, e.g. using a highlighter that one would otherwise not be able to do.
