x "y z" w
[lex]    "x" "y z" "w"
[parse]  (AND (AND "x" "y z") "w")
[gen]    (x:(pos=1) AND (y:(pos=2) PHRASE 2 z:(pos=3)) AND w:(pos=4))

x "y z
[lex]    "x" "y z"
[parse]  (AND "x" "y z")
[gen]    (x:(pos=1) AND (y:(pos=2) PHRASE 2 z:(pos=3)))

x "" y
[lex]    "x" "" "y"
[parse]  (AND (AND "x" "") "y")
[gen]    (x:(pos=1) AND y:(pos=2))

x "  " y
[lex]    "x" "  " "y"
[parse]  (AND (AND "x" "  ") "y")
[gen]    (x:(pos=1) AND y:(pos=2))

lit:" x y"
[lex]    PREFIX/lit " x y"
[parse]  (FILTER (PREFIX/lit ' x y'))
[gen]    0 * L x y

lit:"x""y"
[lex]    PREFIX/lit "x"y"
[parse]  (FILTER (PREFIX/lit 'x"y'))
[gen]    0 * Lx"y