diff --git a/doc/tutorial/basics/0_intro/10_json.txt b/doc/tutorial/basics/0_intro/10_json.txt
index c8b7ac4..b7815b0 100644
--- a/doc/tutorial/basics/0_intro/10_json.txt
+++ b/doc/tutorial/basics/0_intro/10_json.txt
@@ -2,17 +2,31 @@
 cmp stdout expect-stdout-cue
 
 -- frontmatter.toml --
-title = "Quotes are Optional for Field Names"
+title = "JSON Superset"
 description = ""
 
 -- text.md --
+CUE is a superset of JSON.
+It adds the following conveniences:
+
+- C-style comments,
+- quotes may be omitted from field names without special characters,
+- commas at the end of fields are optional,
+- comma after last element in list is allowed,
+- outer curly braces are optional.
+
+<!--
+{{< alert color="info">}}
+CUE borrows a trick from Go to make commas optional:
+the formal grammar still requires commas,
+but the scanner inserts commas according to a small set
+of simple rules.
+{{< /alert >}}
+-->
+
 JSON objects are called structs in CUE.
 An object member is called a field.
 
-
-Double quotes may be omitted from field names if their name contains no
-special characters and does not start with a number:
-
 -- json.cue --
 one: 1
 two: 2
diff --git a/doc/tutorial/basics/0_intro/20_cue.txt b/doc/tutorial/basics/0_intro/20_cue.txt
index 19579cc..de16e7d 100644
--- a/doc/tutorial/basics/0_intro/20_cue.txt
+++ b/doc/tutorial/basics/0_intro/20_cue.txt
@@ -1,6 +1,6 @@
 
 -- frontmatter.toml --
-title = "Commas are Optional after Fields"
+title = "Types are values"
 description = ""
 
 -- text.md --
diff --git a/doc/tutorial/basics/2_types/20_duplicates.txt b/doc/tutorial/basics/0_intro/30_duplicates.txt
similarity index 82%
rename from doc/tutorial/basics/2_types/20_duplicates.txt
rename to doc/tutorial/basics/0_intro/30_duplicates.txt
index dce9b26..e1187ae 100644
--- a/doc/tutorial/basics/2_types/20_duplicates.txt
+++ b/doc/tutorial/basics/0_intro/30_duplicates.txt
@@ -13,18 +13,14 @@
 For structs, fields are merged and duplicated fields are handled recursively.
 
 For lists, all elements must match accordingly
-([we discuss open-ended lists later](lists.md).)
+<!-- ([we discuss open-ended lists later](lists.md).) -->
 
 -- dup.cue --
 a: 4
 a: 4
 
-s: {
-    x: 1
-}
-s: {
-    y: 2
-}
+s: { b: 2 }
+s: { c: 2 }
 
 l: [ 1, 2 ]
 l: [ 1, 2 ]
@@ -32,7 +28,7 @@
 -- expect-stdout-cue --
 a: 4
 s: {
-    x: 1
-    y: 2
+    b: 2
+    c: 2
 }
 l: [1, 2]
diff --git a/doc/tutorial/basics/0_intro/35_duplicates.txt b/doc/tutorial/basics/0_intro/40_constraints.txt
similarity index 61%
rename from doc/tutorial/basics/0_intro/35_duplicates.txt
rename to doc/tutorial/basics/0_intro/40_constraints.txt
index 4085030..363edaf 100644
--- a/doc/tutorial/basics/0_intro/35_duplicates.txt
+++ b/doc/tutorial/basics/0_intro/40_constraints.txt
@@ -1,4 +1,4 @@
-cue eval dup.cue
+cue eval check.cue
 cmp stdout expect-stdout-cue
 
 -- frontmatter.toml --
@@ -15,27 +15,30 @@
 They can be applied to CUE data, or directly to YAML or JSON.
 
 But constraints can also reduce boilerplate.
-If a constraints defines a concrete value, there is no need
+If a constraint defines a concrete value, there is no need
 to specify it in values to which this constraint applies.
 
--- dup.cue --
-a: 4
-a: 4
-
-s: {
-    x: 1
-}
-s: {
-    y: 2
+-- check.cue --
+schema: {
+    name:  string
+    age:   int
+    human: true // always true
 }
 
-l: [ 1, 2 ]
-l: [ 1, 2 ]
+viola: schema
+viola: {
+    name: "Viola"
+    age:  38
+}
 
 -- expect-stdout-cue --
-a: 4
-s: {
-    x: 1
-    y: 2
+schema: {
+    name:  string
+    age:   int
+    human: true
 }
-l: [1, 2]
+viola: {
+    name:  "Viola"
+    age:   38
+    human: true
+}
diff --git a/doc/tutorial/basics/0_intro/43_schema.txt b/doc/tutorial/basics/0_intro/43_schema.txt
new file mode 100644
index 0000000..0293122
--- /dev/null
+++ b/doc/tutorial/basics/0_intro/43_schema.txt
@@ -0,0 +1,40 @@
+cue export schema.cue
+cmp stdout expect-stdout-cue
+
+-- frontmatter.toml --
+title = "Definitions"
+description = ""
+
+-- text.md --
+In CUE, schema are typically written as Definitions,
+using a `::` instead of `:`.
+This tells CUE that they are to be used for validation and should
+not be output as data; it is okay for them to remain unspecified.
+
+A definition also tells CUE the full set of allowed fields.
+In other words, definitions define "closed" structs.
+Including a `...` in struct keeps it open.
+
+-- schema.cue --
+Conn :: {
+    address:  string
+    port:     int
+    protocol: string
+    // ...    // uncomment this to allow any field
+}
+
+lossy: Conn & {
+    address:  "1.2.3.4"
+    port:     8888
+    protocol: "udp"
+    // foo: 2 // uncomment this to get an error
+}
+
+-- expect-stdout-cue --
+{
+    "lossy": {
+        "address": "1.2.3.4",
+        "port": 8888,
+        "protocol": "udp"
+    }
+}
diff --git a/doc/tutorial/basics/0_intro/32_validation.txt b/doc/tutorial/basics/0_intro/47_validation.txt
similarity index 100%
rename from doc/tutorial/basics/0_intro/32_validation.txt
rename to doc/tutorial/basics/0_intro/47_validation.txt
diff --git a/doc/tutorial/basics/0_intro/30_order.txt b/doc/tutorial/basics/0_intro/50_order.txt
similarity index 88%
rename from doc/tutorial/basics/0_intro/30_order.txt
rename to doc/tutorial/basics/0_intro/50_order.txt
index b38cd3e..e7b2e7c 100644
--- a/doc/tutorial/basics/0_intro/30_order.txt
+++ b/doc/tutorial/basics/0_intro/50_order.txt
@@ -13,8 +13,6 @@
 that makes it easy for humans _and_ machines to reason over values and
 makes advanced tooling and automation possible.
 
-If you can think of an example where order matters, it is not valid CUE.
-
 -- order.cue --
 a: {x: 1, y: int}
 a: {x: int, y: 2}
diff --git a/doc/tutorial/basics/0_intro/40_fold.txt b/doc/tutorial/basics/0_intro/55_fold.txt
similarity index 100%
rename from doc/tutorial/basics/0_intro/40_fold.txt
rename to doc/tutorial/basics/0_intro/55_fold.txt
diff --git a/doc/tutorial/basics/0_intro/50_boilerplate.txt b/doc/tutorial/basics/0_intro/80_boilerplate.txt
similarity index 93%
rename from doc/tutorial/basics/0_intro/50_boilerplate.txt
rename to doc/tutorial/basics/0_intro/80_boilerplate.txt
index 2924ee4..75ed27b 100644
--- a/doc/tutorial/basics/0_intro/50_boilerplate.txt
+++ b/doc/tutorial/basics/0_intro/80_boilerplate.txt
@@ -1,7 +1,8 @@
 
 -- frontmatter.toml --
-title = "Templating"
+title = "Boilerplate"
 description = ""
+draft = true
 
 -- text.md --
 Constraints specify what values are allowed.
diff --git a/doc/tutorial/basics/2_types/50_disjunctions.txt b/doc/tutorial/basics/2_types/50_disjunctions.txt
index 81a7eda..99bb955 100644
--- a/doc/tutorial/basics/2_types/50_disjunctions.txt
+++ b/doc/tutorial/basics/2_types/50_disjunctions.txt
@@ -14,20 +14,20 @@
 to define anything else than these two values.
 
 -- disjunctions.cue --
-conn: {
+Conn :: {
     address:  string
     port:     int
     protocol: "tcp" | "udp"
 }
 
-lossy: conn & {
+lossy: Conn & {
     address:  "1.2.3.4"
     port:     8888
     protocol: "udp"
 }
 
 -- expect-stdout-cue --
-conn: {
+Conn :: {
     address:  string
     port:     int
     protocol: "tcp" | "udp"
diff --git a/doc/tutorial/basics/2_types/75_rangedef.txt b/doc/tutorial/basics/2_types/75_bounddef.txt
similarity index 92%
rename from doc/tutorial/basics/2_types/75_rangedef.txt
rename to doc/tutorial/basics/2_types/75_bounddef.txt
index 1ef0b89..3125ff7 100644
--- a/doc/tutorial/basics/2_types/75_rangedef.txt
+++ b/doc/tutorial/basics/2_types/75_bounddef.txt
@@ -1,15 +1,15 @@
-cue eval -i range.cue
+cue eval -i bound.cue
 cmp stdout expect-stdout-cue
 
 -- frontmatter.toml --
-title = "Predefined Ranges"
+title = "Predefined Bounds"
 description = ""
 
 -- text.md --
 CUE numbers have arbitrary precision.
 Also there is no unsigned integer type.
 
-CUE defines the following predefined identifiers to restrict the ranges of
+CUE defines the following predefined identifiers to restrict the bounds of
 integers to common values.
 
 ```
@@ -28,7 +28,7 @@
 uint128   >=0 & <=340_282_366_920_938_463_463_374_607_431_768_211_455
 ```
 
--- range.cue --
+-- bound.cue --
 positive: uint
 byte:     uint8
 word:     int32
diff --git a/doc/tutorial/basics/2_types/20_selectors.txt b/doc/tutorial/basics/4_references/20_selectors.txt
similarity index 100%
rename from doc/tutorial/basics/2_types/20_selectors.txt
rename to doc/tutorial/basics/4_references/20_selectors.txt