Validating a Tag


I am using the acts_as_taggable_on plugin (which derivates from acts_as_taggable_on_steroids). My question is: How can I validate that my tags doesn't have any special characters such as . / \ etc. It seems this validations are not included in the plugin. Can you give me any guide in which is the best way to make this validations?

Thanks again,


Anyone can point me in a direction?