Year: {{{field| Year|input type=regexp|regexp=/^\d{4}$!^$/|size=4|message=The year field can accept only integers and must be 4 digits in length!}}}
Year: {{{field| Year|input type=regexp|regexp=/^\d{4}$!^$/|size=4|message=The year field can accept only integers and must be 4 digits in length!}}}