Mention the procedure of PCT filing.

The Patent Cooperation Treaty (PCT) provides a streamlined and centralized procedure for filing international patent applications, facilitating the process of seeking patent protection in multiple countries through a single application. The PCT system is administered by the World Intellectual Property Organization (WIPO) and offers several advantages, including simplified filing procedures, extended time for national phase entry, and international search and preliminary examination services. Here's an overview of the procedure for filing a PCT application:

1. Determine Eligibility and Patentable Subject Matter:
   Before filing a PCT application, it's essential to ensure that the invention meets the eligibility requirements for international patent protection and constitutes patentable subject matter under the PCT and national patent laws. The invention must be novel, non-obvious, and industrially applicable to qualify for patent protection.

2. Select Receiving Office (RO):
   The first step in the PCT filing process is to select a Receiving Office (RO) where the international patent application will be filed. The applicant can choose any competent RO, typically the national patent office of the applicant's country of residence or a designated PCT receiving office.

3. Prepare International Patent Application:
   The applicant prepares the international patent application according to the requirements of the PCT and the selected RO. The application includes a description of the invention, claims defining the scope of protection sought, drawings (if necessary), and any required forms or documents specified by the RO.

4. Submit PCT Application to Receiving Office:
   The completed international patent application is submitted to the selected RO either electronically or in paper form, along with the requisite filing fees. The RO conducts a formal examination to ensure that the application meets the minimum requirements for international filing and assigns an international application number and filing date.

5. International Search:
   After receiving the international patent application, the RO forwards the application to an International Searching Authority (ISA) chosen by the applicant or appointed by WIPO. The ISA conducts an international search to identify prior art documents relevant to the claimed invention and prepares an international search report (ISR) and a written opinion on patentability.

6. Publication of International Application:
   The international patent application is published by WIPO approximately 18 months from the priority date or the filing date, whichever is earlier. The publication makes the contents of the application available to the public and allows interested parties to review the invention and submit observations or comments.

7. International Preliminary Examination (Optional):
   The applicant may request an international preliminary examination (IPE) to obtain a preliminary assessment of the patentability of the invention. The IPE is conducted by an International Preliminary Examining Authority (IPEA) based on the international search report, the written opinion, and any amendments or arguments submitted by the applicant.

8. National Phase Entry:
   Following the international phase, the applicant enters the national phase by filing national or regional patent applications in each desired contracting state or regional patent office within the prescribed time limit. The PCT application serves as the basis for national or regional applications, providing the priority date and the international search and examination reports.

Overall, the PCT filing procedure offers a convenient and cost-effective mechanism for pursuing international patent protection, enabling applicants to delay the expenses associated with filing multiple national applications while obtaining a preliminary assessment of patentability through the international search and examination process. By harmonizing and simplifying patent procedures across multiple jurisdictions, the PCT system promotes global innovation and facilitates the international exchange of technology and knowledge.