A more thorough explanation:

Definition: Signum is a Latin word that was used in Roman law. It means a sign or a seal. In written documents, signum was a stamp that was put on to close a document. This was done to protect the contents of the document from unauthorized people and to prevent forgery. Signum was also used at the end of a document to show that the person who put the seal on it recognized the written declaration as their own. Signum was also used as a seal of a witness who was present at the making of a document.

• When a person signed a legal document, they would also put their signum on it to show that they recognized the contents of the document as their own.
• If a person found a bloodstain on a murder suspect, that could be considered a signum or an indication that the suspect was involved in the crime.

These examples illustrate how signum was used in Roman law to indicate the authenticity of a document or to provide evidence in a legal case.