0 : 0 NB. ================================================== the idea
   'a(.)b|b(.)c' rxmatches 'azb bwc'
 0 3
 1 1
_1 0

 4 3
_1 0
 5 1
   'a(.)b|b(.)c' (rxmatches rxfrom ]) 'azb bwc'
+---+-+-+
|azb|z| |
+---+-+-+
|bwc| |w|
+---+-+-+
   'a(.)b|b(.)c' rxmain@rxmatches 'azb bwc'
0 3

4 3
   'a(.)b|b(.)c' (rxmain@rxmatches rxfrom ]) 'azb bwc'
+---+
|azb|
+---+
|bwc|
+---+
   'a(.)b|b(.)c' rxmain@rxmatch 'azb bwc'
0 3
   'a(.)b|b(.)c' (rxmain@rxmatch rxfrom ]) 'azb bwc'
+---+
|azb|
+---+
)