Define descended where table.route takes it

path.go

@@ -156,9 +156,10 @@ type tableRoute struct {
 	descends bool
 }
 
-// route is how tail passes t, reached from another table where descended. The path
+// route is how tail passes t. descended means the previous route stepped into t
-// reads a row wherever a segment follows or the table was reached from another; a
+// from a row of an ancestor table, so t reads a row even where tail is empty; a
-// table reached whole, with no selector, is left to a render's own draw.
+// table reached otherwise, with no selector and an empty tail, is left to a render's
+// own draw.
 func (t *table) route(tail []string, descended bool) (tableRoute, error) {
 	sel, tail, err := t.selector(tail)
 	if err != nil {

todo.md

@@ -26,8 +26,6 @@ least modify.
 
 This round, in order:
 
-- Define `descended` where `table.route` takes it: five seats reverse-engineered it from
-  the `draw` expression and the four walks' loop condition.
 - Keep a template's table in one field: `template.table` and `template.cell.table` both
   answer which table it belongs to, and `checkOwnFamily` and `traceRead` branch on both.
 - Stop `readField` dereferencing a nil `held`: `renderLeaf` passes nil, safe only