Documentation on MAX10 fiftyfivenm_rublock command

I am still missing something. What is the purpose of the fiftyfivenm_rublock block (which is mentioned in https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/max-10/ug_m10_config.pdf, specifically "2.2.1. Remote System Upgrade" which mentions the rublock as the method of updating through User Logic) ?

Thank you for your reply