initial

The initial filter matches a position if that position is the initial position, the unique position with no parent.
  initial

The initial position itself is the value of the filter

  position 0

Examples

The initial filter is used in Qq-rotations-90-degree.cql, Qq-rotations.cql, averagedistance.cql, excelsior-comment.cql, excelsior-multiple.cql, excelsior-return.cql, excelsior-simple.cql, most-visited-square.cql, most-visited-square-2.cql, multiple-discovered-checks.cql, persistent.cql, rook-corners-1.cql, rook-corners-2.cql, rook-corners-rotate-with-range.cql, and staircase.cql.