From the Wiki @ wiki.mendix.com:
User restrictions is applying context behavior to the current user. You can set the property user restriction on Maintain, None and Apply. When set to apply the logged in user is added to the context of the Reference selector or Reference set selector. E.g. when a user logs in and wants to select tasks in a Reference selector or Reference set selector, he will be only able to see his own tasks (when there is an association between user and this specific tasks). When set to None, the logged in user is completely removed from the context; e.g. the user will be able to view all objects (tasks) in the Reference selector or Reference set selector. When set on Maintain (default value) the context is kept.
Keep in mind that userRestriction is in fact a Depricated property from some of the first releases. If you want to constrain the datagrid on the user that is logged in you could beter use a xpath constraint to have more control over the actual behaviour.
This properties has some side effects. It also applies the user constraint to all forms opened by the grid, so automatically the forms opened by your new and edit button are constrainted the current user
In my case I want to restrict the displayed records per the owner, so should I use this restriction property to do this restriction, or you recommend to use the Xpath? to display the records created by logged in user.