BOL BOL, no Match "" at beginning of line.
MBOL BOL, no Same, assuming multiline.
SBOL BOL, no Same, assuming singleline.
+EOS EOL, no Match "" at end of string.
EOL EOL, no Match "" at end of line.
MEOL EOL, no Same, assuming multiline.
SEOL EOL, no Same, assuming singleline.