// Download forced-moves-both-sides.cql
// PGN output when run on sample.pgn

Find games with the longest sequence of consecutive forced moves that
are actually made

This is a rare case where the version 6.1 version is clearer. We
cannot use

  {countmoves legal -- == 1} +

because the repetition signal '+' only applies to the right-most preceding
dash constituent, and here there are none. Likewise,

  {countmoves legal  == 1}

would fail because the trailing '+' would only apply to the  .

That is why we enclose the filter and dash inside a chain. 

cql(input hhdbvi.pgn)
sort "most forced moves"
  ({countmoves legal  == 1}