Siemens SIMATIC S7 F Manual page 160

Programming
The overall signature and the date of the last compilation appear in the printout of
the fail-safe program, which is important for the on-site acceptance of the Safety
Program (e.g. by an outside expert). The overall signature of the compiled Safety
Program appears twice in the printout: once in the program information section as
a value of the block container and once in the footer as a value from the source
(see "Checking the Overall Signatures" in the section entitled "Initial Acceptance of
a Safety Program").
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Fail-Safe Systems
A5E00085588-03