User talk:69.62.164.112

April 2019
Hello, I'm ST47. I wanted to let you know that I reverted one of your recent contributions —specifically this edit to Diffraction grating— because it did not appear constructive. If you would like to experiment, please use the sandbox. If you have any questions, you can ask for assistance at the Help Desk. Thanks. ST47 (talk) 00:49, 11 April 2019 (UTC)
 * If this is a shared IP address, and you did not make the edits, consider creating an account for yourself or logging in with an existing account so you can avoid further irrelevant notices.