An or filter has the form
    left or right
where left and right are filters. It matches the position if either left matches the position or right matches the position. For example,
    check or Ra3
is true in a position if either one side is in check in the position or if a white rook is on a3 or both.

If left matches the position, then right is not evaluated.


The or filter is used in several examples such as castleecho.cql, chameleon.cql, idealmate.cql, and others.