diff --git a/c/reg_test/expected/out b/c/reg_test/expected/out
index 4640e36ae..85ae9a7fc 100644
--- a/c/reg_test/expected/out
+++ b/c/reg_test/expected/out
@@ -16604,8 +16604,2070 @@ NR k logging4
 ================================================================
 DSL BREAK/CONTINUE IN NESTED FOR-SREC
 
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    break;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    before
+2  a    before
+3  a    before
+4  a    before
+5  a    before
+6  a    before
+7  a    before
+8  a    before
+9  a    before
+10 a    before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    continue;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    before
+1  b    before
+1  i    before
+1  x    before
+1  y    before
+2  a    before
+2  b    before
+2  i    before
+2  x    before
+2  y    before
+3  a    before
+3  b    before
+3  i    before
+3  x    before
+3  y    before
+4  a    before
+4  b    before
+4  i    before
+4  x    before
+4  y    before
+5  a    before
+5  b    before
+5  i    before
+5  x    before
+5  y    before
+6  a    before
+6  b    before
+6  i    before
+6  x    before
+6  y    before
+7  a    before
+7  b    before
+7  i    before
+7  x    before
+7  y    before
+8  a    before
+8  b    before
+8  i    before
+8  x    before
+8  y    before
+9  a    before
+9  b    before
+9  i    before
+9  x    before
+9  y    before
+10 a    before
+10 b    before
+10 i    before
+10 x    before
+10 y    before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      break;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    pan
+1  i    1
+1  x    0.3467901443380824
+1  y    0.7268028627434533
+2  a    eks
+2  b    pan
+2  i    2
+2  x    0.7586799647899636
+2  y    0.5221511083334797
+3  a    wye
+3  b    wye
+3  i    3
+3  x    0.20460330576630303
+3  y    0.33831852551664776
+4  a    eks
+4  b    wye
+4  i    4
+4  x    0.38139939387114097
+4  y    0.13418874328430463
+5  a    wye
+5  b    pan
+5  i    5
+5  x    0.5732889198020006
+5  y    0.8636244699032729
+6  a    zee
+6  b    pan
+6  i    6
+6  x    0.5271261600918548
+6  y    0.49322128674835697
+7  a    eks
+7  b    zee
+7  i    7
+7  x    0.6117840605678454
+7  y    0.1878849191181694
+8  a    zee
+8  b    wye
+8  i    8
+8  x    0.5985540091064224
+8  y    0.976181385699006
+9  a    hat
+9  b    wye
+9  i    9
+9  x    0.03144187646093577
+9  y    0.7495507603507059
+10 a    pan
+10 b    wye
+10 i    10
+10 x    0.5026260055412137
+10 y    0.9526183602969864
+
+NR names output2
+1  a_a   before
+1  b_a   before
+1  i_a   before
+1  x_a   before
+1  y_a   before
+2  a_a   before
+2  b_a   before
+2  i_a   before
+2  x_a   before
+2  y_a   before
+3  a_a   before
+3  b_a   before
+3  i_a   before
+3  x_a   before
+3  y_a   before
+4  a_a   before
+4  b_a   before
+4  i_a   before
+4  x_a   before
+4  y_a   before
+5  a_a   before
+5  b_a   before
+5  i_a   before
+5  x_a   before
+5  y_a   before
+6  a_a   before
+6  b_a   before
+6  i_a   before
+6  x_a   before
+6  y_a   before
+7  a_a   before
+7  b_a   before
+7  i_a   before
+7  x_a   before
+7  y_a   before
+8  a_a   before
+8  b_a   before
+8  i_a   before
+8  x_a   before
+8  y_a   before
+9  a_a   before
+9  b_a   before
+9  i_a   before
+9  x_a   before
+9  y_a   before
+10 a_a   before
+10 b_a   before
+10 i_a   before
+10 x_a   before
+10 y_a   before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      continue;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    pan
+1  i    1
+1  x    0.3467901443380824
+1  y    0.7268028627434533
+2  a    eks
+2  b    pan
+2  i    2
+2  x    0.7586799647899636
+2  y    0.5221511083334797
+3  a    wye
+3  b    wye
+3  i    3
+3  x    0.20460330576630303
+3  y    0.33831852551664776
+4  a    eks
+4  b    wye
+4  i    4
+4  x    0.38139939387114097
+4  y    0.13418874328430463
+5  a    wye
+5  b    pan
+5  i    5
+5  x    0.5732889198020006
+5  y    0.8636244699032729
+6  a    zee
+6  b    pan
+6  i    6
+6  x    0.5271261600918548
+6  y    0.49322128674835697
+7  a    eks
+7  b    zee
+7  i    7
+7  x    0.6117840605678454
+7  y    0.1878849191181694
+8  a    zee
+8  b    wye
+8  i    8
+8  x    0.5985540091064224
+8  y    0.976181385699006
+9  a    hat
+9  b    wye
+9  i    9
+9  x    0.03144187646093577
+9  y    0.7495507603507059
+10 a    pan
+10 b    wye
+10 i    10
+10 x    0.5026260055412137
+10 y    0.9526183602969864
+
+NR names output2
+1  a_a   before
+1  a_b   before
+1  a_i   before
+1  a_x   before
+1  a_y   before
+1  b_a   before
+1  b_b   before
+1  b_i   before
+1  b_x   before
+1  b_y   before
+1  i_a   before
+1  i_b   before
+1  i_i   before
+1  i_x   before
+1  i_y   before
+1  x_a   before
+1  x_b   before
+1  x_i   before
+1  x_x   before
+1  x_y   before
+1  y_a   before
+1  y_b   before
+1  y_i   before
+1  y_x   before
+1  y_y   before
+2  a_a   before
+2  a_b   before
+2  a_i   before
+2  a_x   before
+2  a_y   before
+2  b_a   before
+2  b_b   before
+2  b_i   before
+2  b_x   before
+2  b_y   before
+2  i_a   before
+2  i_b   before
+2  i_i   before
+2  i_x   before
+2  i_y   before
+2  x_a   before
+2  x_b   before
+2  x_i   before
+2  x_x   before
+2  x_y   before
+2  y_a   before
+2  y_b   before
+2  y_i   before
+2  y_x   before
+2  y_y   before
+3  a_a   before
+3  a_b   before
+3  a_i   before
+3  a_x   before
+3  a_y   before
+3  b_a   before
+3  b_b   before
+3  b_i   before
+3  b_x   before
+3  b_y   before
+3  i_a   before
+3  i_b   before
+3  i_i   before
+3  i_x   before
+3  i_y   before
+3  x_a   before
+3  x_b   before
+3  x_i   before
+3  x_x   before
+3  x_y   before
+3  y_a   before
+3  y_b   before
+3  y_i   before
+3  y_x   before
+3  y_y   before
+4  a_a   before
+4  a_b   before
+4  a_i   before
+4  a_x   before
+4  a_y   before
+4  b_a   before
+4  b_b   before
+4  b_i   before
+4  b_x   before
+4  b_y   before
+4  i_a   before
+4  i_b   before
+4  i_i   before
+4  i_x   before
+4  i_y   before
+4  x_a   before
+4  x_b   before
+4  x_i   before
+4  x_x   before
+4  x_y   before
+4  y_a   before
+4  y_b   before
+4  y_i   before
+4  y_x   before
+4  y_y   before
+5  a_a   before
+5  a_b   before
+5  a_i   before
+5  a_x   before
+5  a_y   before
+5  b_a   before
+5  b_b   before
+5  b_i   before
+5  b_x   before
+5  b_y   before
+5  i_a   before
+5  i_b   before
+5  i_i   before
+5  i_x   before
+5  i_y   before
+5  x_a   before
+5  x_b   before
+5  x_i   before
+5  x_x   before
+5  x_y   before
+5  y_a   before
+5  y_b   before
+5  y_i   before
+5  y_x   before
+5  y_y   before
+6  a_a   before
+6  a_b   before
+6  a_i   before
+6  a_x   before
+6  a_y   before
+6  b_a   before
+6  b_b   before
+6  b_i   before
+6  b_x   before
+6  b_y   before
+6  i_a   before
+6  i_b   before
+6  i_i   before
+6  i_x   before
+6  i_y   before
+6  x_a   before
+6  x_b   before
+6  x_i   before
+6  x_x   before
+6  x_y   before
+6  y_a   before
+6  y_b   before
+6  y_i   before
+6  y_x   before
+6  y_y   before
+7  a_a   before
+7  a_b   before
+7  a_i   before
+7  a_x   before
+7  a_y   before
+7  b_a   before
+7  b_b   before
+7  b_i   before
+7  b_x   before
+7  b_y   before
+7  i_a   before
+7  i_b   before
+7  i_i   before
+7  i_x   before
+7  i_y   before
+7  x_a   before
+7  x_b   before
+7  x_i   before
+7  x_x   before
+7  x_y   before
+7  y_a   before
+7  y_b   before
+7  y_i   before
+7  y_x   before
+7  y_y   before
+8  a_a   before
+8  a_b   before
+8  a_i   before
+8  a_x   before
+8  a_y   before
+8  b_a   before
+8  b_b   before
+8  b_i   before
+8  b_x   before
+8  b_y   before
+8  i_a   before
+8  i_b   before
+8  i_i   before
+8  i_x   before
+8  i_y   before
+8  x_a   before
+8  x_b   before
+8  x_i   before
+8  x_x   before
+8  x_y   before
+8  y_a   before
+8  y_b   before
+8  y_i   before
+8  y_x   before
+8  y_y   before
+9  a_a   before
+9  a_b   before
+9  a_i   before
+9  a_x   before
+9  a_y   before
+9  b_a   before
+9  b_b   before
+9  b_i   before
+9  b_x   before
+9  b_y   before
+9  i_a   before
+9  i_b   before
+9  i_i   before
+9  i_x   before
+9  i_y   before
+9  x_a   before
+9  x_b   before
+9  x_i   before
+9  x_x   before
+9  x_y   before
+9  y_a   before
+9  y_b   before
+9  y_i   before
+9  y_x   before
+9  y_y   before
+10 a_a   before
+10 a_b   before
+10 a_i   before
+10 a_x   before
+10 a_y   before
+10 b_a   before
+10 b_b   before
+10 b_i   before
+10 b_x   before
+10 b_y   before
+10 i_a   before
+10 i_b   before
+10 i_i   before
+10 i_x   before
+10 i_y   before
+10 x_a   before
+10 x_b   before
+10 x_i   before
+10 x_x   before
+10 x_y   before
+10 y_a   before
+10 y_b   before
+10 y_i   before
+10 y_x   before
+10 y_y   before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    break;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      break;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    before
+2  a    before
+3  a    before
+4  a    before
+5  a    before
+6  a    before
+7  a    before
+8  a    before
+9  a    before
+10 a    before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    continue;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      break;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    before
+1  b    before
+1  i    before
+1  x    before
+1  y    before
+2  a    before
+2  b    before
+2  i    before
+2  x    before
+2  y    before
+3  a    before
+3  b    before
+3  i    before
+3  x    before
+3  y    before
+4  a    before
+4  b    before
+4  i    before
+4  x    before
+4  y    before
+5  a    before
+5  b    before
+5  i    before
+5  x    before
+5  y    before
+6  a    before
+6  b    before
+6  i    before
+6  x    before
+6  y    before
+7  a    before
+7  b    before
+7  i    before
+7  x    before
+7  y    before
+8  a    before
+8  b    before
+8  i    before
+8  x    before
+8  y    before
+9  a    before
+9  b    before
+9  i    before
+9  x    before
+9  y    before
+10 a    before
+10 b    before
+10 i    before
+10 x    before
+10 y    before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    break;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      continue;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    before
+2  a    before
+3  a    before
+4  a    before
+5  a    before
+6  a    before
+7  a    before
+8  a    before
+9  a    before
+10 a    before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    continue;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      continue;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    before
+1  b    before
+1  i    before
+1  x    before
+1  y    before
+2  a    before
+2  b    before
+2  i    before
+2  x    before
+2  y    before
+3  a    before
+3  b    before
+3  i    before
+3  x    before
+3  y    before
+4  a    before
+4  b    before
+4  i    before
+4  x    before
+4  y    before
+5  a    before
+5  b    before
+5  i    before
+5  x    before
+5  y    before
+6  a    before
+6  b    before
+6  i    before
+6  x    before
+6  y    before
+7  a    before
+7  b    before
+7  i    before
+7  x    before
+7  y    before
+8  a    before
+8  b    before
+8  i    before
+8  x    before
+8  y    before
+9  a    before
+9  b    before
+9  i    before
+9  x    before
+9  y    before
+10 a    before
+10 b    before
+10 i    before
+10 x    before
+10 y    before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        break
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    before
+2  a    eks
+2  b    before
+3  a    wye
+3  b    before
+4  a    eks
+4  b    before
+5  a    wye
+5  b    before
+6  a    zee
+6  b    before
+7  a    eks
+7  b    before
+8  a    zee
+8  b    before
+9  a    hat
+9  b    before
+10 a    pan
+10 b    before
+
+NR names output2
+1  a_a   pan
+1  a_b   pan
+1  a_i   1
+1  a_x   0.3467901443380824
+1  a_y   0.7268028627434533
+2  a_a   eks
+2  a_b   pan
+2  a_i   2
+2  a_x   0.7586799647899636
+2  a_y   0.5221511083334797
+3  a_a   wye
+3  a_b   wye
+3  a_i   3
+3  a_x   0.20460330576630303
+3  a_y   0.33831852551664776
+4  a_a   eks
+4  a_b   wye
+4  a_i   4
+4  a_x   0.38139939387114097
+4  a_y   0.13418874328430463
+5  a_a   wye
+5  a_b   pan
+5  a_i   5
+5  a_x   0.5732889198020006
+5  a_y   0.8636244699032729
+6  a_a   zee
+6  a_b   pan
+6  a_i   6
+6  a_x   0.5271261600918548
+6  a_y   0.49322128674835697
+7  a_a   eks
+7  a_b   zee
+7  a_i   7
+7  a_x   0.6117840605678454
+7  a_y   0.1878849191181694
+8  a_a   zee
+8  a_b   wye
+8  a_i   8
+8  a_x   0.5985540091064224
+8  a_y   0.976181385699006
+9  a_a   hat
+9  a_b   wye
+9  a_i   9
+9  a_x   0.03144187646093577
+9  a_y   0.7495507603507059
+10 a_a   pan
+10 a_b   wye
+10 a_i   10
+10 a_x   0.5026260055412137
+10 a_y   0.9526183602969864
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        continue
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    before
+1  i    1
+1  x    0.3467901443380824
+1  y    0.7268028627434533
+2  a    eks
+2  b    before
+2  i    2
+2  x    0.7586799647899636
+2  y    0.5221511083334797
+3  a    wye
+3  b    before
+3  i    3
+3  x    0.20460330576630303
+3  y    0.33831852551664776
+4  a    eks
+4  b    before
+4  i    4
+4  x    0.38139939387114097
+4  y    0.13418874328430463
+5  a    wye
+5  b    before
+5  i    5
+5  x    0.5732889198020006
+5  y    0.8636244699032729
+6  a    zee
+6  b    before
+6  i    6
+6  x    0.5271261600918548
+6  y    0.49322128674835697
+7  a    eks
+7  b    before
+7  i    7
+7  x    0.6117840605678454
+7  y    0.1878849191181694
+8  a    zee
+8  b    before
+8  i    8
+8  x    0.5985540091064224
+8  y    0.976181385699006
+9  a    hat
+9  b    before
+9  i    9
+9  x    0.03144187646093577
+9  y    0.7495507603507059
+10 a    pan
+10 b    before
+10 i    10
+10 x    0.5026260055412137
+10 y    0.9526183602969864
+
+NR names output2
+1  a_a   pan
+1  a_b   pan
+1  a_i   1
+1  a_x   0.3467901443380824
+1  a_y   0.7268028627434533
+1  i_a   pan
+1  i_b   pan
+1  i_i   1
+1  i_x   0.3467901443380824
+1  i_y   0.7268028627434533
+1  x_a   pan
+1  x_b   pan
+1  x_i   1
+1  x_x   0.3467901443380824
+1  x_y   0.7268028627434533
+1  y_a   pan
+1  y_b   pan
+1  y_i   1
+1  y_x   0.3467901443380824
+1  y_y   0.7268028627434533
+2  a_a   eks
+2  a_b   pan
+2  a_i   2
+2  a_x   0.7586799647899636
+2  a_y   0.5221511083334797
+2  i_a   eks
+2  i_b   pan
+2  i_i   2
+2  i_x   0.7586799647899636
+2  i_y   0.5221511083334797
+2  x_a   eks
+2  x_b   pan
+2  x_i   2
+2  x_x   0.7586799647899636
+2  x_y   0.5221511083334797
+2  y_a   eks
+2  y_b   pan
+2  y_i   2
+2  y_x   0.7586799647899636
+2  y_y   0.5221511083334797
+3  a_a   wye
+3  a_b   wye
+3  a_i   3
+3  a_x   0.20460330576630303
+3  a_y   0.33831852551664776
+3  i_a   wye
+3  i_b   wye
+3  i_i   3
+3  i_x   0.20460330576630303
+3  i_y   0.33831852551664776
+3  x_a   wye
+3  x_b   wye
+3  x_i   3
+3  x_x   0.20460330576630303
+3  x_y   0.33831852551664776
+3  y_a   wye
+3  y_b   wye
+3  y_i   3
+3  y_x   0.20460330576630303
+3  y_y   0.33831852551664776
+4  a_a   eks
+4  a_b   wye
+4  a_i   4
+4  a_x   0.38139939387114097
+4  a_y   0.13418874328430463
+4  i_a   eks
+4  i_b   wye
+4  i_i   4
+4  i_x   0.38139939387114097
+4  i_y   0.13418874328430463
+4  x_a   eks
+4  x_b   wye
+4  x_i   4
+4  x_x   0.38139939387114097
+4  x_y   0.13418874328430463
+4  y_a   eks
+4  y_b   wye
+4  y_i   4
+4  y_x   0.38139939387114097
+4  y_y   0.13418874328430463
+5  a_a   wye
+5  a_b   pan
+5  a_i   5
+5  a_x   0.5732889198020006
+5  a_y   0.8636244699032729
+5  i_a   wye
+5  i_b   pan
+5  i_i   5
+5  i_x   0.5732889198020006
+5  i_y   0.8636244699032729
+5  x_a   wye
+5  x_b   pan
+5  x_i   5
+5  x_x   0.5732889198020006
+5  x_y   0.8636244699032729
+5  y_a   wye
+5  y_b   pan
+5  y_i   5
+5  y_x   0.5732889198020006
+5  y_y   0.8636244699032729
+6  a_a   zee
+6  a_b   pan
+6  a_i   6
+6  a_x   0.5271261600918548
+6  a_y   0.49322128674835697
+6  i_a   zee
+6  i_b   pan
+6  i_i   6
+6  i_x   0.5271261600918548
+6  i_y   0.49322128674835697
+6  x_a   zee
+6  x_b   pan
+6  x_i   6
+6  x_x   0.5271261600918548
+6  x_y   0.49322128674835697
+6  y_a   zee
+6  y_b   pan
+6  y_i   6
+6  y_x   0.5271261600918548
+6  y_y   0.49322128674835697
+7  a_a   eks
+7  a_b   zee
+7  a_i   7
+7  a_x   0.6117840605678454
+7  a_y   0.1878849191181694
+7  i_a   eks
+7  i_b   zee
+7  i_i   7
+7  i_x   0.6117840605678454
+7  i_y   0.1878849191181694
+7  x_a   eks
+7  x_b   zee
+7  x_i   7
+7  x_x   0.6117840605678454
+7  x_y   0.1878849191181694
+7  y_a   eks
+7  y_b   zee
+7  y_i   7
+7  y_x   0.6117840605678454
+7  y_y   0.1878849191181694
+8  a_a   zee
+8  a_b   wye
+8  a_i   8
+8  a_x   0.5985540091064224
+8  a_y   0.976181385699006
+8  i_a   zee
+8  i_b   wye
+8  i_i   8
+8  i_x   0.5985540091064224
+8  i_y   0.976181385699006
+8  x_a   zee
+8  x_b   wye
+8  x_i   8
+8  x_x   0.5985540091064224
+8  x_y   0.976181385699006
+8  y_a   zee
+8  y_b   wye
+8  y_i   8
+8  y_x   0.5985540091064224
+8  y_y   0.976181385699006
+9  a_a   hat
+9  a_b   wye
+9  a_i   9
+9  a_x   0.03144187646093577
+9  a_y   0.7495507603507059
+9  i_a   hat
+9  i_b   wye
+9  i_i   9
+9  i_x   0.03144187646093577
+9  i_y   0.7495507603507059
+9  x_a   hat
+9  x_b   wye
+9  x_i   9
+9  x_x   0.03144187646093577
+9  x_y   0.7495507603507059
+9  y_a   hat
+9  y_b   wye
+9  y_i   9
+9  y_x   0.03144187646093577
+9  y_y   0.7495507603507059
+10 a_a   pan
+10 a_b   wye
+10 a_i   10
+10 a_x   0.5026260055412137
+10 a_y   0.9526183602969864
+10 i_a   pan
+10 i_b   wye
+10 i_i   10
+10 i_x   0.5026260055412137
+10 i_y   0.9526183602969864
+10 x_a   pan
+10 x_b   wye
+10 x_i   10
+10 x_x   0.5026260055412137
+10 x_y   0.9526183602969864
+10 y_a   pan
+10 y_b   wye
+10 y_i   10
+10 y_x   0.5026260055412137
+10 y_y   0.9526183602969864
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          break
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    pan
+1  i    1
+1  x    0.3467901443380824
+1  y    0.7268028627434533
+2  a    eks
+2  b    pan
+2  i    2
+2  x    0.7586799647899636
+2  y    0.5221511083334797
+3  a    wye
+3  b    wye
+3  i    3
+3  x    0.20460330576630303
+3  y    0.33831852551664776
+4  a    eks
+4  b    wye
+4  i    4
+4  x    0.38139939387114097
+4  y    0.13418874328430463
+5  a    wye
+5  b    pan
+5  i    5
+5  x    0.5732889198020006
+5  y    0.8636244699032729
+6  a    zee
+6  b    pan
+6  i    6
+6  x    0.5271261600918548
+6  y    0.49322128674835697
+7  a    eks
+7  b    zee
+7  i    7
+7  x    0.6117840605678454
+7  y    0.1878849191181694
+8  a    zee
+8  b    wye
+8  i    8
+8  x    0.5985540091064224
+8  y    0.976181385699006
+9  a    hat
+9  b    wye
+9  i    9
+9  x    0.03144187646093577
+9  y    0.7495507603507059
+10 a    pan
+10 b    wye
+10 i    10
+10 x    0.5026260055412137
+10 y    0.9526183602969864
+
+NR names output2
+1  a_a   before
+1  b_a   before
+1  i_a   before
+1  x_a   before
+1  y_a   before
+2  a_a   before
+2  b_a   before
+2  i_a   before
+2  x_a   before
+2  y_a   before
+3  a_a   before
+3  b_a   before
+3  i_a   before
+3  x_a   before
+3  y_a   before
+4  a_a   before
+4  b_a   before
+4  i_a   before
+4  x_a   before
+4  y_a   before
+5  a_a   before
+5  b_a   before
+5  i_a   before
+5  x_a   before
+5  y_a   before
+6  a_a   before
+6  b_a   before
+6  i_a   before
+6  x_a   before
+6  y_a   before
+7  a_a   before
+7  b_a   before
+7  i_a   before
+7  x_a   before
+7  y_a   before
+8  a_a   before
+8  b_a   before
+8  i_a   before
+8  x_a   before
+8  y_a   before
+9  a_a   before
+9  b_a   before
+9  i_a   before
+9  x_a   before
+9  y_a   before
+10 a_a   before
+10 b_a   before
+10 i_a   before
+10 x_a   before
+10 y_a   before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "b") {
+          continue
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    pan
+1  i    1
+1  x    0.3467901443380824
+1  y    0.7268028627434533
+2  a    eks
+2  b    pan
+2  i    2
+2  x    0.7586799647899636
+2  y    0.5221511083334797
+3  a    wye
+3  b    wye
+3  i    3
+3  x    0.20460330576630303
+3  y    0.33831852551664776
+4  a    eks
+4  b    wye
+4  i    4
+4  x    0.38139939387114097
+4  y    0.13418874328430463
+5  a    wye
+5  b    pan
+5  i    5
+5  x    0.5732889198020006
+5  y    0.8636244699032729
+6  a    zee
+6  b    pan
+6  i    6
+6  x    0.5271261600918548
+6  y    0.49322128674835697
+7  a    eks
+7  b    zee
+7  i    7
+7  x    0.6117840605678454
+7  y    0.1878849191181694
+8  a    zee
+8  b    wye
+8  i    8
+8  x    0.5985540091064224
+8  y    0.976181385699006
+9  a    hat
+9  b    wye
+9  i    9
+9  x    0.03144187646093577
+9  y    0.7495507603507059
+10 a    pan
+10 b    wye
+10 i    10
+10 x    0.5026260055412137
+10 y    0.9526183602969864
+
+NR names output2
+1  a_a   pan
+1  a_b   before
+1  a_i   1
+1  a_x   0.3467901443380824
+1  a_y   0.7268028627434533
+1  b_a   pan
+1  b_b   before
+1  b_i   1
+1  b_x   0.3467901443380824
+1  b_y   0.7268028627434533
+1  i_a   pan
+1  i_b   before
+1  i_i   1
+1  i_x   0.3467901443380824
+1  i_y   0.7268028627434533
+1  x_a   pan
+1  x_b   before
+1  x_i   1
+1  x_x   0.3467901443380824
+1  x_y   0.7268028627434533
+1  y_a   pan
+1  y_b   before
+1  y_i   1
+1  y_x   0.3467901443380824
+1  y_y   0.7268028627434533
+2  a_a   eks
+2  a_b   before
+2  a_i   2
+2  a_x   0.7586799647899636
+2  a_y   0.5221511083334797
+2  b_a   eks
+2  b_b   before
+2  b_i   2
+2  b_x   0.7586799647899636
+2  b_y   0.5221511083334797
+2  i_a   eks
+2  i_b   before
+2  i_i   2
+2  i_x   0.7586799647899636
+2  i_y   0.5221511083334797
+2  x_a   eks
+2  x_b   before
+2  x_i   2
+2  x_x   0.7586799647899636
+2  x_y   0.5221511083334797
+2  y_a   eks
+2  y_b   before
+2  y_i   2
+2  y_x   0.7586799647899636
+2  y_y   0.5221511083334797
+3  a_a   wye
+3  a_b   before
+3  a_i   3
+3  a_x   0.20460330576630303
+3  a_y   0.33831852551664776
+3  b_a   wye
+3  b_b   before
+3  b_i   3
+3  b_x   0.20460330576630303
+3  b_y   0.33831852551664776
+3  i_a   wye
+3  i_b   before
+3  i_i   3
+3  i_x   0.20460330576630303
+3  i_y   0.33831852551664776
+3  x_a   wye
+3  x_b   before
+3  x_i   3
+3  x_x   0.20460330576630303
+3  x_y   0.33831852551664776
+3  y_a   wye
+3  y_b   before
+3  y_i   3
+3  y_x   0.20460330576630303
+3  y_y   0.33831852551664776
+4  a_a   eks
+4  a_b   before
+4  a_i   4
+4  a_x   0.38139939387114097
+4  a_y   0.13418874328430463
+4  b_a   eks
+4  b_b   before
+4  b_i   4
+4  b_x   0.38139939387114097
+4  b_y   0.13418874328430463
+4  i_a   eks
+4  i_b   before
+4  i_i   4
+4  i_x   0.38139939387114097
+4  i_y   0.13418874328430463
+4  x_a   eks
+4  x_b   before
+4  x_i   4
+4  x_x   0.38139939387114097
+4  x_y   0.13418874328430463
+4  y_a   eks
+4  y_b   before
+4  y_i   4
+4  y_x   0.38139939387114097
+4  y_y   0.13418874328430463
+5  a_a   wye
+5  a_b   before
+5  a_i   5
+5  a_x   0.5732889198020006
+5  a_y   0.8636244699032729
+5  b_a   wye
+5  b_b   before
+5  b_i   5
+5  b_x   0.5732889198020006
+5  b_y   0.8636244699032729
+5  i_a   wye
+5  i_b   before
+5  i_i   5
+5  i_x   0.5732889198020006
+5  i_y   0.8636244699032729
+5  x_a   wye
+5  x_b   before
+5  x_i   5
+5  x_x   0.5732889198020006
+5  x_y   0.8636244699032729
+5  y_a   wye
+5  y_b   before
+5  y_i   5
+5  y_x   0.5732889198020006
+5  y_y   0.8636244699032729
+6  a_a   zee
+6  a_b   before
+6  a_i   6
+6  a_x   0.5271261600918548
+6  a_y   0.49322128674835697
+6  b_a   zee
+6  b_b   before
+6  b_i   6
+6  b_x   0.5271261600918548
+6  b_y   0.49322128674835697
+6  i_a   zee
+6  i_b   before
+6  i_i   6
+6  i_x   0.5271261600918548
+6  i_y   0.49322128674835697
+6  x_a   zee
+6  x_b   before
+6  x_i   6
+6  x_x   0.5271261600918548
+6  x_y   0.49322128674835697
+6  y_a   zee
+6  y_b   before
+6  y_i   6
+6  y_x   0.5271261600918548
+6  y_y   0.49322128674835697
+7  a_a   eks
+7  a_b   before
+7  a_i   7
+7  a_x   0.6117840605678454
+7  a_y   0.1878849191181694
+7  b_a   eks
+7  b_b   before
+7  b_i   7
+7  b_x   0.6117840605678454
+7  b_y   0.1878849191181694
+7  i_a   eks
+7  i_b   before
+7  i_i   7
+7  i_x   0.6117840605678454
+7  i_y   0.1878849191181694
+7  x_a   eks
+7  x_b   before
+7  x_i   7
+7  x_x   0.6117840605678454
+7  x_y   0.1878849191181694
+7  y_a   eks
+7  y_b   before
+7  y_i   7
+7  y_x   0.6117840605678454
+7  y_y   0.1878849191181694
+8  a_a   zee
+8  a_b   before
+8  a_i   8
+8  a_x   0.5985540091064224
+8  a_y   0.976181385699006
+8  b_a   zee
+8  b_b   before
+8  b_i   8
+8  b_x   0.5985540091064224
+8  b_y   0.976181385699006
+8  i_a   zee
+8  i_b   before
+8  i_i   8
+8  i_x   0.5985540091064224
+8  i_y   0.976181385699006
+8  x_a   zee
+8  x_b   before
+8  x_i   8
+8  x_x   0.5985540091064224
+8  x_y   0.976181385699006
+8  y_a   zee
+8  y_b   before
+8  y_i   8
+8  y_x   0.5985540091064224
+8  y_y   0.976181385699006
+9  a_a   hat
+9  a_b   before
+9  a_i   9
+9  a_x   0.03144187646093577
+9  a_y   0.7495507603507059
+9  b_a   hat
+9  b_b   before
+9  b_i   9
+9  b_x   0.03144187646093577
+9  b_y   0.7495507603507059
+9  i_a   hat
+9  i_b   before
+9  i_i   9
+9  i_x   0.03144187646093577
+9  i_y   0.7495507603507059
+9  x_a   hat
+9  x_b   before
+9  x_i   9
+9  x_x   0.03144187646093577
+9  x_y   0.7495507603507059
+9  y_a   hat
+9  y_b   before
+9  y_i   9
+9  y_x   0.03144187646093577
+9  y_y   0.7495507603507059
+10 a_a   pan
+10 a_b   before
+10 a_i   10
+10 a_x   0.5026260055412137
+10 a_y   0.9526183602969864
+10 b_a   pan
+10 b_b   before
+10 b_i   10
+10 b_x   0.5026260055412137
+10 b_y   0.9526183602969864
+10 i_a   pan
+10 i_b   before
+10 i_i   10
+10 i_x   0.5026260055412137
+10 i_y   0.9526183602969864
+10 x_a   pan
+10 x_b   before
+10 x_i   10
+10 x_x   0.5026260055412137
+10 x_y   0.9526183602969864
+10 y_a   pan
+10 y_b   before
+10 y_i   10
+10 y_x   0.5026260055412137
+10 y_y   0.9526183602969864
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        break
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          break
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    before
+2  a    eks
+2  b    before
+3  a    wye
+3  b    before
+4  a    eks
+4  b    before
+5  a    wye
+5  b    before
+6  a    zee
+6  b    before
+7  a    eks
+7  b    before
+8  a    zee
+8  b    before
+9  a    hat
+9  b    before
+10 a    pan
+10 b    before
+
+NR names output2
+1  a_a   before
+2  a_a   before
+3  a_a   before
+4  a_a   before
+5  a_a   before
+6  a_a   before
+7  a_a   before
+8  a_a   before
+9  a_a   before
+10 a_a   before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        continue
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          break
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    before
+1  i    1
+1  x    0.3467901443380824
+1  y    0.7268028627434533
+2  a    eks
+2  b    before
+2  i    2
+2  x    0.7586799647899636
+2  y    0.5221511083334797
+3  a    wye
+3  b    before
+3  i    3
+3  x    0.20460330576630303
+3  y    0.33831852551664776
+4  a    eks
+4  b    before
+4  i    4
+4  x    0.38139939387114097
+4  y    0.13418874328430463
+5  a    wye
+5  b    before
+5  i    5
+5  x    0.5732889198020006
+5  y    0.8636244699032729
+6  a    zee
+6  b    before
+6  i    6
+6  x    0.5271261600918548
+6  y    0.49322128674835697
+7  a    eks
+7  b    before
+7  i    7
+7  x    0.6117840605678454
+7  y    0.1878849191181694
+8  a    zee
+8  b    before
+8  i    8
+8  x    0.5985540091064224
+8  y    0.976181385699006
+9  a    hat
+9  b    before
+9  i    9
+9  x    0.03144187646093577
+9  y    0.7495507603507059
+10 a    pan
+10 b    before
+10 i    10
+10 x    0.5026260055412137
+10 y    0.9526183602969864
+
+NR names output2
+1  a_a   before
+1  i_a   before
+1  x_a   before
+1  y_a   before
+2  a_a   before
+2  i_a   before
+2  x_a   before
+2  y_a   before
+3  a_a   before
+3  i_a   before
+3  x_a   before
+3  y_a   before
+4  a_a   before
+4  i_a   before
+4  x_a   before
+4  y_a   before
+5  a_a   before
+5  i_a   before
+5  x_a   before
+5  y_a   before
+6  a_a   before
+6  i_a   before
+6  x_a   before
+6  y_a   before
+7  a_a   before
+7  i_a   before
+7  x_a   before
+7  y_a   before
+8  a_a   before
+8  i_a   before
+8  x_a   before
+8  y_a   before
+9  a_a   before
+9  i_a   before
+9  x_a   before
+9  y_a   before
+10 a_a   before
+10 i_a   before
+10 x_a   before
+10 y_a   before
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        break
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          continue
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    before
+2  a    eks
+2  b    before
+3  a    wye
+3  b    before
+4  a    eks
+4  b    before
+5  a    wye
+5  b    before
+6  a    zee
+6  b    before
+7  a    eks
+7  b    before
+8  a    zee
+8  b    before
+9  a    hat
+9  b    before
+10 a    pan
+10 b    before
+
+NR names output2
+1  a_a   before
+1  a_b   pan
+1  a_i   1
+1  a_x   0.3467901443380824
+1  a_y   0.7268028627434533
+2  a_a   before
+2  a_b   pan
+2  a_i   2
+2  a_x   0.7586799647899636
+2  a_y   0.5221511083334797
+3  a_a   before
+3  a_b   wye
+3  a_i   3
+3  a_x   0.20460330576630303
+3  a_y   0.33831852551664776
+4  a_a   before
+4  a_b   wye
+4  a_i   4
+4  a_x   0.38139939387114097
+4  a_y   0.13418874328430463
+5  a_a   before
+5  a_b   pan
+5  a_i   5
+5  a_x   0.5732889198020006
+5  a_y   0.8636244699032729
+6  a_a   before
+6  a_b   pan
+6  a_i   6
+6  a_x   0.5271261600918548
+6  a_y   0.49322128674835697
+7  a_a   before
+7  a_b   zee
+7  a_i   7
+7  a_x   0.6117840605678454
+7  a_y   0.1878849191181694
+8  a_a   before
+8  a_b   wye
+8  a_i   8
+8  a_x   0.5985540091064224
+8  a_y   0.976181385699006
+9  a_a   before
+9  a_b   wye
+9  a_i   9
+9  a_x   0.03144187646093577
+9  a_y   0.7495507603507059
+10 a_a   before
+10 a_b   wye
+10 a_i   10
+10 a_x   0.5026260055412137
+10 a_y   0.9526183602969864
+
+mlr --opprint --from ./reg_test/input/abixy put -q 
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        continue
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          continue
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+
+NR name output1
+1  a    pan
+1  b    before
+1  i    1
+1  x    0.3467901443380824
+1  y    0.7268028627434533
+2  a    eks
+2  b    before
+2  i    2
+2  x    0.7586799647899636
+2  y    0.5221511083334797
+3  a    wye
+3  b    before
+3  i    3
+3  x    0.20460330576630303
+3  y    0.33831852551664776
+4  a    eks
+4  b    before
+4  i    4
+4  x    0.38139939387114097
+4  y    0.13418874328430463
+5  a    wye
+5  b    before
+5  i    5
+5  x    0.5732889198020006
+5  y    0.8636244699032729
+6  a    zee
+6  b    before
+6  i    6
+6  x    0.5271261600918548
+6  y    0.49322128674835697
+7  a    eks
+7  b    before
+7  i    7
+7  x    0.6117840605678454
+7  y    0.1878849191181694
+8  a    zee
+8  b    before
+8  i    8
+8  x    0.5985540091064224
+8  y    0.976181385699006
+9  a    hat
+9  b    before
+9  i    9
+9  x    0.03144187646093577
+9  y    0.7495507603507059
+10 a    pan
+10 b    before
+10 i    10
+10 x    0.5026260055412137
+10 y    0.9526183602969864
+
+NR names output2
+1  a_a   before
+1  a_b   pan
+1  a_i   1
+1  a_x   0.3467901443380824
+1  a_y   0.7268028627434533
+1  i_a   before
+1  i_b   pan
+1  i_i   1
+1  i_x   0.3467901443380824
+1  i_y   0.7268028627434533
+1  x_a   before
+1  x_b   pan
+1  x_i   1
+1  x_x   0.3467901443380824
+1  x_y   0.7268028627434533
+1  y_a   before
+1  y_b   pan
+1  y_i   1
+1  y_x   0.3467901443380824
+1  y_y   0.7268028627434533
+2  a_a   before
+2  a_b   pan
+2  a_i   2
+2  a_x   0.7586799647899636
+2  a_y   0.5221511083334797
+2  i_a   before
+2  i_b   pan
+2  i_i   2
+2  i_x   0.7586799647899636
+2  i_y   0.5221511083334797
+2  x_a   before
+2  x_b   pan
+2  x_i   2
+2  x_x   0.7586799647899636
+2  x_y   0.5221511083334797
+2  y_a   before
+2  y_b   pan
+2  y_i   2
+2  y_x   0.7586799647899636
+2  y_y   0.5221511083334797
+3  a_a   before
+3  a_b   wye
+3  a_i   3
+3  a_x   0.20460330576630303
+3  a_y   0.33831852551664776
+3  i_a   before
+3  i_b   wye
+3  i_i   3
+3  i_x   0.20460330576630303
+3  i_y   0.33831852551664776
+3  x_a   before
+3  x_b   wye
+3  x_i   3
+3  x_x   0.20460330576630303
+3  x_y   0.33831852551664776
+3  y_a   before
+3  y_b   wye
+3  y_i   3
+3  y_x   0.20460330576630303
+3  y_y   0.33831852551664776
+4  a_a   before
+4  a_b   wye
+4  a_i   4
+4  a_x   0.38139939387114097
+4  a_y   0.13418874328430463
+4  i_a   before
+4  i_b   wye
+4  i_i   4
+4  i_x   0.38139939387114097
+4  i_y   0.13418874328430463
+4  x_a   before
+4  x_b   wye
+4  x_i   4
+4  x_x   0.38139939387114097
+4  x_y   0.13418874328430463
+4  y_a   before
+4  y_b   wye
+4  y_i   4
+4  y_x   0.38139939387114097
+4  y_y   0.13418874328430463
+5  a_a   before
+5  a_b   pan
+5  a_i   5
+5  a_x   0.5732889198020006
+5  a_y   0.8636244699032729
+5  i_a   before
+5  i_b   pan
+5  i_i   5
+5  i_x   0.5732889198020006
+5  i_y   0.8636244699032729
+5  x_a   before
+5  x_b   pan
+5  x_i   5
+5  x_x   0.5732889198020006
+5  x_y   0.8636244699032729
+5  y_a   before
+5  y_b   pan
+5  y_i   5
+5  y_x   0.5732889198020006
+5  y_y   0.8636244699032729
+6  a_a   before
+6  a_b   pan
+6  a_i   6
+6  a_x   0.5271261600918548
+6  a_y   0.49322128674835697
+6  i_a   before
+6  i_b   pan
+6  i_i   6
+6  i_x   0.5271261600918548
+6  i_y   0.49322128674835697
+6  x_a   before
+6  x_b   pan
+6  x_i   6
+6  x_x   0.5271261600918548
+6  x_y   0.49322128674835697
+6  y_a   before
+6  y_b   pan
+6  y_i   6
+6  y_x   0.5271261600918548
+6  y_y   0.49322128674835697
+7  a_a   before
+7  a_b   zee
+7  a_i   7
+7  a_x   0.6117840605678454
+7  a_y   0.1878849191181694
+7  i_a   before
+7  i_b   zee
+7  i_i   7
+7  i_x   0.6117840605678454
+7  i_y   0.1878849191181694
+7  x_a   before
+7  x_b   zee
+7  x_i   7
+7  x_x   0.6117840605678454
+7  x_y   0.1878849191181694
+7  y_a   before
+7  y_b   zee
+7  y_i   7
+7  y_x   0.6117840605678454
+7  y_y   0.1878849191181694
+8  a_a   before
+8  a_b   wye
+8  a_i   8
+8  a_x   0.5985540091064224
+8  a_y   0.976181385699006
+8  i_a   before
+8  i_b   wye
+8  i_i   8
+8  i_x   0.5985540091064224
+8  i_y   0.976181385699006
+8  x_a   before
+8  x_b   wye
+8  x_i   8
+8  x_x   0.5985540091064224
+8  x_y   0.976181385699006
+8  y_a   before
+8  y_b   wye
+8  y_i   8
+8  y_x   0.5985540091064224
+8  y_y   0.976181385699006
+9  a_a   before
+9  a_b   wye
+9  a_i   9
+9  a_x   0.03144187646093577
+9  a_y   0.7495507603507059
+9  i_a   before
+9  i_b   wye
+9  i_i   9
+9  i_x   0.03144187646093577
+9  i_y   0.7495507603507059
+9  x_a   before
+9  x_b   wye
+9  x_i   9
+9  x_x   0.03144187646093577
+9  x_y   0.7495507603507059
+9  y_a   before
+9  y_b   wye
+9  y_i   9
+9  y_x   0.03144187646093577
+9  y_y   0.7495507603507059
+10 a_a   before
+10 a_b   wye
+10 a_i   10
+10 a_x   0.5026260055412137
+10 a_y   0.9526183602969864
+10 i_a   before
+10 i_b   wye
+10 i_i   10
+10 i_x   0.5026260055412137
+10 i_y   0.9526183602969864
+10 x_a   before
+10 x_b   wye
+10 x_i   10
+10 x_x   0.5026260055412137
+10 x_y   0.9526183602969864
+10 y_a   before
+10 y_b   wye
+10 y_i   10
+10 y_x   0.5026260055412137
+10 y_y   0.9526183602969864
 
----------------------------------------------------------------- xxx to do after bcstack impl
 
 ================================================================
 FOR-OOSVAR DEPTH TESTS
diff --git a/c/reg_test/run b/c/reg_test/run
index 0cd971fd8..6056a6f65 100755
--- a/c/reg_test/run
+++ b/c/reg_test/run
@@ -1902,7 +1902,303 @@ run_mlr --opprint --from $indir/abixy put -q '
 # ----------------------------------------------------------------
 announce DSL BREAK/CONTINUE IN NESTED FOR-SREC
 
-mention xxx to do after bcstack impl
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    break;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    continue;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      break;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      continue;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+# ----------------------------------------------------------------
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    break;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      break;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    continue;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      break;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    break;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      continue;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    continue;
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      continue;
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+
+# ----------------------------------------------------------------
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        break
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        continue
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          break
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "b") {
+          continue
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+# ----------------------------------------------------------------
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        break
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          break
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        continue
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          break
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        break
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          continue
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
+run_mlr --opprint --from $indir/abixy put -q '
+  for (k1, v1 in $*) {
+    @output1[NR][k1] = "before";
+    if (k1 == "b") {
+        continue
+    }
+    @output1[NR][k1] = v1;
+    for (k2, v2 in $*) {
+      @output2[NR][k1."_".k2] = "before";
+      if (k2 == "a") {
+          continue
+      }
+      @output2[NR][k1."_".k2] = v2;
+    }
+  }
+  end {
+    emit @output1, "NR", "name";
+    emit @output2, "NR", "names";
+  }
+'
+
 
 # ----------------------------------------------------------------
 announce FOR-OOSVAR DEPTH TESTS
diff --git a/c/todo.txt b/c/todo.txt
index def5679da..61bc714d4 100644
--- a/c/todo.txt
+++ b/c/todo.txt
@@ -10,7 +10,6 @@ TOP-OF-LIST SUMMARY
   - in-loop stack flags for handlers (at pvars?)
   - test break & continue both set
   ! bcstack! push at entry to each loop. test w/ nested break out of nested loops.
-? do-while: continue -- execute expr-test?
 ! cst_statement_free bring up to date with blank_alloc
 
 ! xxxes
@@ -31,6 +30,7 @@ TOP-OF-LIST SUMMARY
 ! extend mld:ref:put, and cookbook
 ! cmt ast/cst stuff re (1) .y; (2) reg_test/expected/out
 * readme note re head dev: announced features ok if build passing (and it is); unannounced features may change
+! clear in doc re semicolon as statement separator, not terminator; blank line doesn't terminate. in its own subsubsection.
 * lemon note/message-wording re resolvable conflicts
 
 ? triple-for with boundvars? or at least faqent re oosvars & while-loops