<b>Sharing teaching materials between classes</b>.
<p>
!href cmd=help&special_parm=neighbor Neighboring classes
 can selectively share teaching materials with each other.
</p><p>
Shared teaching materials are identical in all the classes sharing them. 
This means that if they are modified in one class, all the
other sharing classes will see the same modification.
</p><p>
For example, a shared message board will show all the messages sent from all
sharing classes. Also, if participant accounts are shared with several
classes, a participant registering into one class will automatically be 
registered in all the others. If the participant's password is modified in
one class, the modified password will be applied in all the other classes too. 
The same is true for supervisor account sharing, but this is
!href cmd=help&special_parm=supshare particularly dangerous
.
</p><p>
If worksheets or exam sheets are shared, all the sharing classes will have
the same worksheet content and score severity, but worksheet opening information
is not shared. If the supervisor opens the score registration of
a shared worksheet for his class, score registrations of the same worksheet in
other classes will remain closed.
</p><p>
Among classes sharing the same type of teaching materials, there must be one
originating the sharing (it is the one where the teaching materials are physically located).
All the other classes will share these teaching materials of the originating
class. Cascaded sharing is not supported.
</p><p>
It is the responsibility of the originating class to declare classes
!href cmd=help&special_parm=sharable allowed to use
its teaching materials. Then it is up to the other sharing classes to actually start
or stop the effective share. The originating class cannot stop existing
active sharing (because this would modify the setup of the other class(es)).
</p><p>
If you want to share teaching materials with another class, the corresponding teaching
materials in your own class must be empty. Due to the fact that many teaching 
materials cannot be cleaned due to
!href cmd=help&special_parm=dependencies inter-dependences
 between different types of teaching materials, teaching materials sharings should
be installed
only at the setup stage of the classes. In general, once participant
activities have started, many teaching materials sharings are no longer possible.
</p><p>
On the other hand, a secondary sharing class can
!href cmd=help&special_parm=stopshare stop the sharing
 at any moment. However, for the above reason, it may not be able to start sharing 
with a class with which you have stopped sharing.
</p>
