what does "signed in the plate" in reference to a seriolithograph mean

Hello.


"What does "Signed in the Plate" mean?
This is the artist's signature which has been made in the printing
plate and is printed along with the image. This is not to be confused
with an original signature."
source: Ask the Expert - New Orleans posters
http://neworleansposters.com/cgi-bin/store/shop.cgi?page=expert.html&cart_id=271368.75008


"Signed in the Plate - Instead of signing each print in pencil, the
artist signs in the plate in which case the signature appears
printed."
source: What is an original print?
http://www.dshprintmaker.com/Print.html


"A print is said to be signed in the plate if the artist's signature
is incorporated into the matrix and so appears as part of the printed
image."
source: DICTIONARY OF PRINTMAKING TERMS
http://www.ahpcs.org/Library/diction-ta.htm

"The very earliest prints were not signed at all, although by the
later part of the fifteenth century many artists indicated their
authorship of a print by incorporating a signature or monogram into
the matrix design, what is called "signed in the plate" or a "plate
signature."'
source: What is a print?
http://www.evabreuerartdealer.com.au/print.html

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