Dynamic value in Content Model

Refer to below links

http://ecmarchitect.com/archives/2008/08/13/845
http://govindaroul.blogspot.in/2013/10/dynamic-list-constraints-in-alfresco.html
http://blog.arvixe.com/custom-constrains-in-alfresco-model/

 https://forums.alfresco.com/forum/developer-discussions/technical-architecture-discussion/dynamic-list-constraint-08212012-1521

https://forums.alfresco.com/forum/general/non-technical-alfresco-discussion/jean-barmash-blog-03212012-0222
https://forums.alfresco.com/forum/developer-discussions/repository-services/custom-constraint-03262008-1636#p140018
http://wiki.alfresco.com/wiki/Forms_Examples
https://forums.alfresco.com/forum/general/non-technical-alfresco-discussion/jean-barmash-blog-03212012-0222