Yes. Adobe Systems Inc. created the PDF file format and owns the copyrights on the data structures, operators, and written specification for PDF. Adobe wishes to make PDF an open standard, so they have given permission to anyone to write software that creates PDF files. The have also given royalty free licenses to the patents if used to create PDF files. Information on this policy is in section 1.7 of the PDF specification published by Adobe, and also at http://partners.adobe.com/public/developer/support/topic_legal_notices.html.