Elon Musk and Grimes tweaked their baby’s unusual name -- but not by much. Musk, the CEO of Tesla, and Grimes, a singer, decided to comply with California health codes and the state constitution, which says only the 26 alphabetical characters of the English language can be used, USA Today reported. Sunday on Instagram, Grimes told her followers that the couple had slightly changed their son’s name from “X Æ A-12” to “X Æ A-Xii.” “Roman numerals,” Grimes said. “Looks better tbh ... one dash is allowed.” Musk shared photos of his newborn son on May 5, a day after Grimes gave birth, People reported. After the couple announced the boy’s name, California officials said the unusual name was not allowed. “A name like ‘X Æ A-12’ would not be allowed,” Matt Conens, of the Office of Public Affairs of the California Department of Public Health, wrote in an email to USA Today. “Vital records must be completed with the 26 alphabetical characters of the English language and appropriate punctuation such as hyphens, apostrophes, periods, and commas.” Those rules are spelled out in the department’s handbook. So, what does the baby’s name mean? Grimes, whose real name is Claire Elise Boucher, said the 'X' stands for “the unknown variable,” CNN reported. 'Æ' is the Elven spelling of AI, or shorthand for artificial intelligence and the word for “love” in several languages, including Japanese. “A-12 = precursor to SR-17 (our favorite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent,” Grimes said. The 'A' in the name also represents “Archangel,” which is Grimes’ favorite song, CNN reported.