Platoons were just implemented in Battlelog for Battlefield 4, I created the platoon and added everyone in my friends list to the platoon, also made a custom emblem for the platoon, once you join the platoon it will add your tags and will make your emblem the clan emblem (see above). This is by default, you can however go to your profile and edit your emblem to show your personalized emblem like before. Using the clan emblem isn't mandatory but I think having a "branding" for our clan isn't a bad idea. If you didn't get the invite you can apply to join here: