Hello, Papayapal! Welcome to Wikipedia! Thank you for your contributions. You may benefit from following some of the links below, which will help you get the most out of Wikipedia. If you have any questions you can ask me on my talk page, or place {{helpme}} on your talk page and ask your question there. Please remember to sign your name on talk pages by clicking or by typing four tildes "~~~~"; this will automatically produce your name and the date. If you are already excited about Wikipedia, you might want to consider being "adopted" by a more experienced editor or joining a WikiProject to collaborate with others in creating and improving articles of your interest. Click here for a directory of all the WikiProjects. Finally, please do your best to always fill in the edit summary field when making edits to pages. Happy editing! Doug Wellertalk06:50, 28 August 2019 (UTC)[reply]
The manual of style you quote says "Apply Wikipedia:Manual of Style § Retaining existing styles with regard to changes from one era to the other." And that link says "The Arbitration Committee has expressed the principle that "When either of two styles are [sic] acceptable it is inappropriate for a Wikipedia editor to change from one style to another unless there is some substantial reason for the change."[3] If you believe an alternative style would be more appropriate for a particular article, discuss this at the article's talk page or – if it raises an issue of more general application or with the MoS itself – at the MoS talk page." The article was changed to BCE in 2012. Doug Wellertalk06:53, 28 August 2019 (UTC)[reply]