This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP
Determines if seek case-insensitively matches the initial substring of string , i.e. string is at least as long as seek and the corresponding characters match.
string seek AnchorISearch post match true
string seek AnchorISearch string false
As for AnchorSearch, but comparisons are case insensitive.