At first sight, you may think it's just another fork of already available module
on drupal.org like taxonomy_access or tac_lite. First one is a taxonomy control
access based on roles, second one is a taxonomy control access based on users. But
both of those modules miss the - according to me essential - inheritance notion :
if you have access to one term, you don't automatically have access to the children
nodes. My module does take care about inheritance and this way permit a powerfull
user access control.

Description:
For this description, I will try to illustrate the module with the following term
scheme:
     1 (root) -> 2 -> 4
                   -> 5 -> 7
              -> 3 -> 6

The basic idea of inheritance is : if you have access to one term then you may
access all children terms.

So I provided 4 different grant access for this module:
  - grant_view
    Which controls whether the user may view nodes associated to this term
  - grant_update
    Which controls whether the user may add nodes associated to this term or edit
    them
  - grant_delete
    Which controls whether the user may delete nodes associated to this term
  - grant_admin
    Which is the most particular grant out of the four.

The last grant access (grant_admin) permits a user to "delegate" control of an access
over a term to another user : if a lambda use has the grant_admin over the term 2, he
may grant view to another user to terms 2, 4, 5 or 7.

So now you are familiar with the possible grant access, if the user lambda have
grant_view on the term 1, then he may view nodes associated with the term 1, 2, 3, 4,
 5, 6 and/or 7. The only record in the database about the grant access is about the
term 1. To reach this goal in a reasonnable amount of time and with simple queries, I
used SQL functions in the DBMS. Availability of those functions is controlled each
time the module is invoked by the hook_init which permit not to break the module even
if the database is transfered to another dbms and if the user has forgot to backup
sql functions :).

Yet another feature of this module is the ability to restrain access to a subtree
while he still have access to the other part. For example, if i set grant_view = 1 to
the term 1 to the user lambda and grant_view = -1 to the term 2, then the user may view
terms 1, 3 and 6 while access to terms 2, 4, 5 and 7 would be denied. The default value
is 0 and it's the value which permits inheritance.


This module also provides a UI to administer the module, views and views handler for
specific fields.

This module could have multiple applications :
  - An e-commerce website where a department supervisor may edit nodes associated to
his department or delegate rights to his employees
  - An news website where the person in charge of the sport section may only create
articles in his own section or may delegate access to the golf area to one specific
person.