An experience has **two kinds of link**, and they are two addresses
rather than a setting to choose between. Both work at the same time.

## The plain link

The one in the header. It follows every future publish, so whoever
holds it always gets your latest work. This is the right link for
nearly everything.

## A version's own link

Copy it from version history, from the row of the version you want. It
goes on serving that version however many times you publish afterwards
— the link for a class sitting an assessment, or a course that has been
signed off.

## Why not Freeze the experience

Because **Freeze** is one answer for everybody. Choosing it for one
class re-points every link already handed out, including the ones you
sent to people who should be seeing your newest version.

Two addresses avoid that entirely: this January's cohort keeps January's
content, everyone else moves on, and you do not have to remember which
setting the experience is in.

## What is frozen, and what is not

Only the **content** is frozen. A learner on a version link meets the
same activities, the same attempt allowances and the same rules as
everyone else, and their work counts towards the same single grade —
one experience is one grade however many links reach it.

So do not use a version link to give a group different rules. Use it
when they must all see the same thing.