So, a C-card is necessary as proof to an operator that he may cater to you w/o getting himself into legal or other trouble in case something where "to happen".
So, if eligibility to dive must be checked by an operator in a no-internet scenario - what is supposed to work and what actually works in practice as proof of certification - and what does not work maybe in ascending order?
- "here's my cert. number ..."
- I brought a printout of a picture front & back of all my cards - have a look, I did not bring my phone.
- ditto, but on phone screen
- I brought a print out of my e-cert - I did not bring my phone.
- ditto, but screen shots of the initial free e-cert on my phone screen (no connection)
- ditto, but the actual paid for e-cert on my phone (if I had any)
- An actual plastic card I created by printing a digital picture of my cert-card (front and back) - or paid someone to do. (probably not distinguishable from the original item (especially when worn) and I think anyone can legally make copies of his/her property for their own personal use to protect the original from wear and tear)
- The actual plastic card as received from the agency.
Obviously, all of the above could easily be faked by replacing one person's pic and name etc. with another's, none are particularly counterfeit proof, but of course fewer people have access to a card printer than all the other stuff. There'd be no point in making counterfeit cards except for "non-internet-scenarios". The wondering point being here is: That being the case, why then isn't a just a picture of the card good enough to begin with?
Again, so, if you are "the operator" (or captain, or DM or instructor or shop owner, or...) and you need to check and there is no internet connection whatsoever, what works as proof for you and what does not?
Why?