FAA rule regarding how to mark your UAS:

Action: Interim final rule.
Summary: This action provides an alternative, streamlined and simple, web-based aircraft registration process for the registration of small unmanned aircraft, including small unmanned aircraft operated as model aircraft, to facilitate compliance with the statutory requirement that all aircraft register prior to operation. It also provides a simpler method for marking small unmanned aircraft that is more appropriate for these aircraft. This action responds to public comments received regarding the proposed registration process in the Operation and Certification of Small Unmanned Aircraft notice of proposed rule making, the request for information regarding unmanned aircraft system registration, and the recommendations from the Unmanned Aircraft System Registration Task Force. The Department encourages persons to participate in this rule making by submitting comments on or before the closing date for comments. The Department will consider all comments received before the closing date and make any necessary amendments as appropriate.
Dates

This rule is effective December 21, 2015. Comments must be received on or before January 15, 2016.

Addresses: Send comments identified by docket number FAA-2015-7396 using any of the following methods:
Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online instructions for sending your comments electronically.

Mail: Send comments to Docket Operations, M-30; U.S. Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room W12-140, West Building Ground Floor, Washington, DC 20590-0001.

Hand Delivery or Courier: Take comments to Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Fax: Fax comments to Docket Operations at 202-493-2251.

Privacy: In accordance with 5 U.S.C. 553(c), DOT solicits comments from the public to better inform its rulemaking process. DOT posts these comments, without edit, including any personal information the commenter provides, to http://www.regulations.gov, as described in the system of records notice (DOT/ALL-14 FDMS), which can be reviewed at http://www.dot.gov/privacy.

Docket: Background documents or comments received may be read at http://www.regulations.gov at any time. Follow the online instructions for accessing the docket or go to the Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For Further Information Contact:
Earl Lawrence, Director, FAA UAS Integration Office, 800 Independence Avenue SW., Washington, DC 20591; telephone (202) 267-6556; email UASRegistration@faa.gov.

Read all about it:
http://www.regulations.gov/#!documentDetail;D=FAA-2015-7396-0001