Register

Read, ask, change. The entries a person reads as a ledger are what a second reader is offered as a few plain questions: find, read, relate. There is one list, not two copies, so there is nothing to keep in step: change an entry once, at the source, and both readers have it at the same moment.

Reading is open to anyone. Changing anything needs a person to approve exactly that change, and a record is kept of who did what, and for whom.