The simple Roman Device known as The Signaculum, is still used today by most Modern Militaries. It is "lovingly" referred to by Soldiers by it's nickname....The "Dog" Tag. Although the term would not be known then, it was coined in the 1930s-40s by American Soldiers, due to it's similar appearance to a Canine Registration Permit Tag, worn on a collar around a Pets neck. In Ancient Rome, Historians are unclear as to just why they were created and used. Seen in the Republic Era, it is thought that The Signaculum were given to Roman Army Recruits who had "passed" their training to join The Legions.
Made of thin lead, they were originally circular in shape. The Soldiers name, "Unit" of assignment and in some cases, "Home" Record, was etched onto the front. The Disc was kept on a small leather or cloth pouch and worn around the neck with a string or leather strap. Failure to wear one's Signaculum merited a serious punishment. As time progressed, the shape of The Signaculum changed to many geometric patterns. No longer kept in a pouch, they were worn fairly the same as Soldiers do today. They also served the same purpose to identify dead Soldiers on the battlefield. Their use would cease after Rome's demise as The World's dominate Power. Their "idea" however - would be "revisited" by Armies many times throughout History. Their use as a primary source of Soldier Identification would not come until the early 20th Century and World War I.
The Signaculum was used to inspire the Roman practice of early Product "Branding" as well. Similar "Tags" were placed on Roman Imports and Exports, as a way of identifying a Maker or Distributor. The name and City of Manufactor was stamped not Signaculum Tags to also identify contacts of Containers. Slaves also wore a type of Signaculum. Often worn on collars around their necks, they were used to identify an Owner. One Historical example read "This Person is a Slave. If found, he has run away. Return to________. You will be Rewarded".