Const
A year filter is an integer 1000..9999, or a string of exactly those four digits (no padding, no leading zero, no sign or decimal point). Anything else would only ever match nothing (a false empty list) or, for "", be skipped (the full list).
A year filter is an integer 1000..9999, or a string of exactly those four digits (no padding, no leading zero, no sign or decimal point). Anything else would only ever match nothing (a false empty list) or, for "", be skipped (the full list).