A more thorough explanation:

PTDL

PTDL stands for Patent and Trademark Depository Library. These are libraries that have been designated by the United States Patent and Trademark Office (USPTO) to provide public access to patent and trademark information.

• The University of Texas at Austin is a PTDL, which means that anyone can go there to access patent and trademark information.
• The PTDL program was established by the USPTO in 1871 to make patent and trademark information more widely available to the public.

These examples illustrate how PTDLs are libraries that have been designated by the USPTO to provide public access to patent and trademark information. They also show that the PTDL program has been around for a long time and is an important part of making patent and trademark information accessible to everyone.