What is the difference between saving and issuing a draft?

Save draft keeps the set-up and adjustments (Save as new leaves an opened draft untouched). Issuing a saved draft freezes it as sent: it is rendered, hashed and stored as that issue's snapshot, so a pack sent to a bank cannot change under it, and a later Compare shows what moved against the live figures. The latest issued copy can be sent for director approval as a Saral Sign envelope; a second click reopens the same envelope instead of filing a duplicate.