diff --git a/cmd/cue/cmd/testdata/script/trim.txt b/cmd/cue/cmd/testdata/script/trim.txt
index a20ddbf..155a14a 100644
--- a/cmd/cue/cmd/testdata/script/trim.txt
+++ b/cmd/cue/cmd/testdata/script/trim.txt
@@ -38,7 +38,7 @@
 
 foo: multipath: {
 	t: [string]: {
-		// Combined with the other template, we know the value must be 5 and
+		// Combined with the other constraints, we know the value must be 5 and
 		// thus the entry below can be eliminated.
 		x: >=5 & <=8
 	}
@@ -95,7 +95,7 @@
 
 foo: multipath: {
 	t: [string]: {
-		// Combined with the other template, we know the value must be 5 and
+		// Combined with the other constraints, we know the value must be 5 and
 		// thus the entry below can be eliminated.
 		x: >=5 & <=8
 	}
diff --git a/cmd/cue/cmd/trim.go b/cmd/cue/cmd/trim.go
index 5101c13..13aaff6 100644
--- a/cmd/cue/cmd/trim.go
+++ b/cmd/cue/cmd/trim.go
@@ -39,13 +39,15 @@
 	cmd := &cobra.Command{
 		Use:   "trim",
 		Short: "remove superfluous fields",
-		Long: `trim removes fields from structs that are already defined by a template
+		Long: `trim removes fields from structs that can be inferred from constraints
 
-A field, struct, or list is removed if it is implied by a template, a list type
-value, a comprehension or any other implied content. It will modify the files
-in place.
+A field, struct, or list is removed if it is implied by a constraint, such
+as from an optional field maching a required field, a list type value,
+a comprehension or any other implied content. It will modify the files in place.
+
 
 Limitations
+
 Removal is on a best effort basis. Some caveats:
 - Fields in implied content may refer to fields within the struct in which
   they are included, but are only resolved on a best-effort basis.
@@ -56,13 +58,13 @@
 Examples:
 
 	$ cat <<EOF > foo.cue
-	light <Name>: {
+	light: [string]: {
 		room:          string
 		brightnessOff: *0.0 | >=0 & <=100.0
 		brightnessOn:  *100.0 | >=0 & <=100.0
 	}
 
-	light ceiling50: {
+	light: ceiling50: {
 		room:          "MasterBedroom"
 		brightnessOff: 0.0    // this line
 		brightnessOn:  100.0  // and this line will be removed
@@ -71,13 +73,13 @@
 
 	$ cue trim foo.cue
 	$ cat foo.cue
-	light <Name>: {
+	light: [string]: {
 		room:          string
 		brightnessOff: *0.0 | >=0 & <=100.0
 		brightnessOn:  *100.0 | >=0 & <=100.0
 	}
 
-	light ceiling50: {
+	light: ceiling50: {
 		room: "MasterBedroom"
 	}
 
@@ -214,7 +216,8 @@
 			}
 
 		case *ast.Field:
-			if _, ok := x.Label.(*ast.TemplateLabel); ok {
+			switch x.Label.(type) {
+			case *ast.TemplateLabel, *ast.ListLit:
 				t.markAlwaysGen(x.Value, false)
 			}
 
@@ -234,7 +237,7 @@
 			t.fromComp[n] = true
 		}
 		if x, ok := n.(*ast.Ident); ok && n != first {
-			// Also mark any value used within a template.
+			// Also mark any value used within a constraint from an optional field.
 			if x.Node != nil {
 				// fmt.Println("MARKED", internal.DebugStr(x.Node),
 				// "by", internal.DebugStr(first))
@@ -271,7 +274,7 @@
 }
 
 // trim strips fields from structs that would otherwise be generated by implied
-// content, such as templates, comprehensions, and list types.
+// content, such as optional fields turned required, comprehensions, and list types.
 //
 // The algorithm walks the tree with two values in parallel: one for the full
 // configuration, and one for implied content. For each node in the tree it
@@ -282,10 +285,10 @@
 // - Fields in the implied content may refer to fields in the complete config.
 //   To support this, incomplete fields are detected and evaluated within the
 //   configuration.
-// - Templates are instantiated as a result of the declaration of concrete
-//   sibling fields. Such fields should not be removed even if the instantiated
-//   template completely subsumes such fields as the reason to instantiate
-//   the template will disappear with it.
+// - Values of optional fields are instantiated as a result of the declaration
+//   of concrete sibling fields. Such fields should not be removed even if the
+//   instantiated constraint completely subsumes such fields as the reason to
+//   apply the optional constraint will disappear with it.
 // - As the parallel structure is different, it may resolve to different
 //   default values. There is no support yet for selecting defaults of a value
 //   based on another value without doing a full unification. So for now we
@@ -313,7 +316,7 @@
 	}
 
 	// Collect generated nodes.
-	// Only keep the good parts of the template.
+	// Only keep the good parts of the optional constraint.
 	// Incoming structs may be incomplete resulting in errors. It is safe
 	// to ignore these. If there is an actual error, it will manifest in
 	// the evaluation of v.
@@ -330,7 +333,7 @@
 
 	switch v.Kind() {
 	case cue.StructKind:
-		// TODO: merge template preprocessing with that of fields.
+		// TODO: merge optional field preprocessing with that of fields.
 
 		// Identify generated components and unify them with the mixin value.
 		exists := false