||Since the beginning of
written language, individuals have affixed their signatures to writings
with the intention of both establishing the source of the writing
and memorializing their assent, or adoption, of its contents. According
The traditional function of a signature is evidential: it is to
give evidence of:
1.The provenance of the document (identity)
2.The intention (will) of an individual with regard to that document
For example, the role of a signature in many consumer contracts
is not solely to provide evidence of the identity of the contracting
party, but rather to additionally provide evidence of deliberation
and informed consent. Signatures may be witnessed and recorded in
the presence of a Notary Public to carry additional legal force.
On legal documents, an illiterate signatory can make a "mark"
(often an "X" but occasionally a personalized symbol),
so long as the document is countersigned by a literate witness.
. . .
Some states’ legal definition of a signature defines a signature
to mean "any memorandum, mark, or sign made with intent to
authenticate any instrument or writing, or the subscription of any
person thereto." In the context of one particular statute,
a signature doesn’t have to be the popular notion of a written
name, but may be other methods of authentication; the intent of
any mark or memorandum makes a signature.