IP addresses and browser User Agent strings are stored for each signature/submission - those are the only measures for 'non-repudiation' currently available.
but i think it doens't differ from other mainstream SaaS solutions - if you read through their terms of services - they put 'non-repudiation' liability on users of their services
but i think it doens't differ from other mainstream SaaS solutions - if you read through their terms of services - they put 'non-repudiation' liability on users of their services