Rename refBinding.key to head, and the stale key wording beside it

drawfence.go

@@ -90,8 +90,8 @@ func checkOwnFamily(t *template) error {
 		seen[n] = true
 		for _, e := range renderEdges(n) {
 			if e.readsRef() {
-				if head, isTable := n.(*template).head(e.read.head).(*table); isTable && head.familyRoot() == own.familyRoot() {
-					return e, head, true
+				if read, isTable := n.(*template).head(e.read.head).(*table); isTable && read.familyRoot() == own.familyRoot() {
+					return e, read, true
 				}
 			}
 			if e, head, found := find(e.to); found {

format.go

@@ -322,11 +322,11 @@ func splitArm(name string, refs map[string]refBinding) arm {
 		if !linked || len(b.tail) == 0 {
 			head := name
 			if linked {
-				head = b.key
+				head = b.head
 			}
 			return arm{spelling: name, head: head, path: head}
 		}
-		return pathArm(name, b.key, b.tail)
+		return pathArm(name, b.head, b.tail)
 	}
 	segs, err := splitPath(name)
 	if err != nil || len(segs) == 1 {
@@ -371,7 +371,7 @@ type callFn func(s *session, emitted string, operands []string) string
 // re-scans the format.
 type op struct {
 	formatToken
-	arms []arm // nameRead: the '|' alternatives, split into key and path once
+	arms []arm // nameRead: the '|' alternatives, split into head and tail once
 	call callFn
 	// operands are the fields the builtin reads, in the order its operands func
 	// fixed; expand reads them before the call. nil for a builtin that reads none.

node.go

@@ -74,7 +74,7 @@ const formatRow = -1
 // templateLink is what a template resolves to in the assembled tree.
 type templateLink struct {
 	refs         map[string]refBinding // each reference the format reads -> what it resolves to
-	refHeads     map[string]node       // each refBinding.key -> the category it names
+	refHeads     map[string]node       // each refBinding.head -> the category it names
 	readsColumn  *columnRead           // set when the format is one reference alone reading a record's column
 	drawGroupKey string                // its draw group keyed by its category: what a render reads its reference paths under
 }

reference.go

@@ -9,10 +9,10 @@ import (
 // data root, {.a} from the folder this file sits in, {..a} from the folder above.
 func isRef(name string) bool { return strings.HasPrefix(name, ".") || strings.HasPrefix(name, "/") }
 
-// refBinding is what a reference resolves to: the key its category is held
+// refBinding is what a reference resolves to: the head its category is held
 // under, and the tail read into it.
 type refBinding struct {
-	key  string
+	head string
 	tail []string
 }
 
@@ -119,15 +119,15 @@ func (t *template) resolveLink(folder []string, path, category string, root map[
 		if err != nil {
 			return link, fmt.Errorf("%s: reference {%s}: %w", path, name, err)
 		}
-		key := "/" + strings.Join(categorySegs, ".")
-		if category != "" && key == "/"+category {
+		head := "/" + strings.Join(categorySegs, ".")
+		if category != "" && head == "/"+category {
 			return link, fmt.Errorf("%s: reference {%s}: names the category it sits in; read a sibling field as a path, or move the shared value into its own category and reference that", path, name)
 		}
-		if err := checkPath(target, tail, key); err != nil {
+		if err := checkPath(target, tail, head); err != nil {
 			return link, fmt.Errorf("%s: reference {%s}: %w", path, name, err)
 		}
-		link.refHeads[key] = target
-		link.refs[name] = refBinding{key, tail}
+		link.refHeads[head] = target
+		link.refs[name] = refBinding{head, tail}
 	}
 	link.readsColumn = columnReadOf(t, link)
 	return link, nil

shape_test.go

@@ -102,7 +102,7 @@ func readsFact(n node) string {
 			}
 		case *template:
 			for _, b := range n.link.refs {
-				set[strings.TrimPrefix(b.key, "/")] = true
+				set[strings.TrimPrefix(b.head, "/")] = true
 			}
 			for _, field := range n.fields {
 				collect(field)