This item in the shortcut menu of an [in development] revision is only available when a model revision is successfully created. Such a revision is saved to the [in development] model revision. The Freeze revision menu item creates a revision from the [in development] revision and makes a new [in development] model revision. In effect it is an unlock and lock operation rolled into one.
The user who freezes the model will be prompted to provide a description for the newly created revision.
Note
That creating a freeze revision will not create a new [current] revision.