an annual initiation is held every year. Some of these state that they are honoraries; others seek to perpetuate the image of a continuing active society where there is none. While there are some guideline criteria for the neutral observer to understand what sort of society any given organization is, much of the analysis reverts to what any one society has been traditionally understood to be. There are additional means, such as societies that were more or less explicitly established in emulation of some previous secret society, or using historical records to show that society X was created out of society Y. Common traits There are several common traits among these societies. For example, many societies have two-part names, such as Skull and Bones or Scroll and Key. Many societies also limit their membership to a specific numerical limit in a class year. Extensive mortuary imagery is associated with many secret societies, maintaining a pretense of great seriousness, and clubhouses are often called "tombs". Tapping The archetypical selection process for entry into a collegiate secret society began at Yale University by a process called tapping. On a publicly announced evening, Yale undergraduates would assemble informally in the College Yard. Current members of Yale's secret societies would walk through the crowd and literally tap a prospective member on the shoulder and then walk with him up to the tapped man's dorm room. There, in private, they would ask him to become a member of their secret society; the inductee had the choice of accepting or rejecting the offer of membership. During this process, it was publicly known who was being tapped for the coming year. Today, the selection process is not quite as formal but is in some ways still public. Now, many societies slip seal-stamped letters under the doors of expecting Juniors, and send cryptic emails to students' inboxes, inviting them to rush parties. Formal tapping days used to exist at Berkeley, and still exist in a much more formal setting at Missouri. Honoraries Several campuses distinguish societies called "honoraries" from secret societies. An honorary is considered to operate in name only: membership is an honor given in recognition of some achievement, and such a society is distinct from a secret society. However, functionally, such organizations can operate identically to secret societies, and historically, most honoraries operated on a secret society basis. Phi Beta Kappa is the best-known such example,