You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Arena_Football_League

Context:
On September 30, 1987, Foster filed an application with the United States Patent and Trademark Office to patent his invented sport. The patent application covered the rules of the game, specifically detailing the goalposts and rebound netting and their impact on gameplay. Foster's application was granted on March 27, 1990. The patent expired on September 30, 2007.

Question:
With whom did Foster file his patent?

the United States Patent and Trademark Office