Crossword puzzle clue "puzzle based on latin squares"

Puzzle based on Latin Squares

Web concerns ... and based on six familiar names hidden in rows 1, 4, 12 and 15 of this puzzle grid, what the black squares in those rows symbolize

Psalm 100 excerpt suggested by six puzzle answers and graphically represented by certain black squares in this puzzle

Poet whose classic work is hidden in this puzzle (see the circled squares of the completed the puzzle)

The squares of "three squares"

Puzzle-within-a-puzzle puzzle

Popular browser extension ... or a literal description of four black squares in this puzzle

Feature of this puzzle that's "fixed" by a literal reading of four squares