Validation issue.

Hi ,

             Am having 3 internal tables.Each table contains constant texts ,Suppose  if the table having different text means i want to display error.

For example,

itab =  'abc-year'

           'bcd-year' 

these are two constant texts,suppose if the internal table contains'

itab =  'xxx-year'

          'bcd-year'     means i have to display error text is wrongly maintained..

Anyone suggest please how to do this.