Help me to implement this plan - limit users to edit content I have a plan that need your help to be implemented.

I am using Drupal 6.x

Let me describe it at first.

We have a content type called it Article

This content type has Title, Description, Link, Status &amp; belongs_to fields.

Title : Title of article record.
Description : brief description of record
Link : the source link [HTML]
Status : the status of record. Available options are FREE , Finished, In progress [it is drop down menu]
Belongs to : it is the name of user that is working on this record. 

At first Some article records are added by admin.
Note: Only admin of site can add new article record.
When the new record is added it has FREE status and doesn't belong to users.

Then a user can select one article record and edit it.
Note : user can edit only the article records that has FREE status .
Also the user is able to edit the record that it is belong to him/her

He/she is able to edit only Status. and set it to another case [in progress , finished or free]

After editing the specific article record, the other users are not able to edit this record.
but the last users who have edited this record is able to edit status field.

after editing a record, the belongs_to field is set to the name of user who has edited it.

For example user1 open a Free status article record and edit it's status to in progress , or finished.

Note: if a user edit his own record' status field from "in progress" to FREE , the belongs_to field is set to empty.

Note: The users are not allowed to edit the records that their status is Finished. [only admin can do it]

There is a page [created by view] that users can see the records. which article records are free, which articles are in progress ? which are finished. and also the users who are working on articles....

Now what is your suggestion to implement this plan?
I would look into the Node Access User Reference module as well as a lot of the other content/node access modules out there, eg, this list off drupal.org.  After getting a good grasp there, it would be up to you to code up the integration of permissions unique to your site, but basically you would need to alter the node forms for this content type, check in there if a user reference is NOT yet set, and if so, set it to user editing the content and then be on your way.