diff --git a/changelog.txt b/changelog.txt
--- a/changelog.txt
+++ b/changelog.txt
@@ -4,3 +4,10 @@
 
 v0.1.2.0 - Add instances (Eq, Show, Generic, Hashable, NFData)
            to classes (BlockTag, BlockTagContent)
+
+v0.1.3.0 - Add:
+    - type TaggedOrBare
+    - class IsTaggedOrBare
+        - type families TaggedType and BareType
+        - isomorphism 'taggedOrBare'
+    - prisms 'tagged' and 'bare'
diff --git a/library/pro-abstract-prelude/Prelude.hs b/library/pro-abstract-prelude/Prelude.hs
--- a/library/pro-abstract-prelude/Prelude.hs
+++ b/library/pro-abstract-prelude/Prelude.hs
@@ -15,7 +15,7 @@
 
 import Containers as X
 
-import BasePrelude as X (Applicative, Bool, Either (..), Eq, Foldable, Functor, Maybe (..), Monad, Monoid (mempty), Ord, Semigroup (..), Show, Traversable, const, either, fmap, maybe, not, pure, traverse, ($), (.), (<$>), (<*>), (=<<), (>>=))
+import BasePrelude as X (Applicative, Bool (..), Either (..), Eq, Foldable, Functor, Maybe (..), Monad, Monoid (mempty), Ord, Semigroup (..), Show, Traversable, const, either, fmap, maybe, not, pure, traverse, ($), (.), (<$>), (<*>), (=<<), (>>=))
 
-import Optics.Core as X (A_Fold, A_Getter, A_Lens, A_Traversal, AffineFold, AffineTraversal, AffineTraversal', An_AffineFold, An_AffineTraversal, An_Iso, Is, Iso, Iso', JoinKinds, Lens, Lens', NoIx, Optic, Optic', OpticKind, Prism', Traversal, Traversal', _Just, _Left, _Right, adjoin, afailing, afolding, atraversal, castOptic, coerced, equality, lens, matching, over, preview, prism', re, review, set, simple, to, traversalVL, traverseOf, traversed, view, (%), JoinKinds)
+import Optics.Core as X (A_Fold, A_Getter, A_Lens, A_Traversal, AffineFold, AffineTraversal, AffineTraversal', An_AffineFold, An_AffineTraversal, An_Iso, Is, Iso, Iso', JoinKinds, Lens, Lens', NoIx, Optic, Optic', OpticKind, Prism', Traversal, Traversal', _Just, _Left, _Right, adjoin, afailing, afolding, atraversal, castOptic, coerced, equality, iso, lens, matching, over, preview, prism', re, review, set, simple, to, traversalVL, traverseOf, traversed, view, (%))
 import Optics.Empty.Core as X (_Empty, pattern Empty)
diff --git a/library/pro-abstract/ProAbstract.hs b/library/pro-abstract/ProAbstract.hs
--- a/library/pro-abstract/ProAbstract.hs
+++ b/library/pro-abstract/ProAbstract.hs
@@ -44,7 +44,7 @@
 
 /Block-level/ content is everything that appears below the document level and above the paragraph level.
 
-- 'Block' = ('fork' : 'Tagged' 'Blocks') ∪ ('plain' : 'Tagged' 'PlainBlock') ∪ ('paragraph' : 'Paragraph')
+- 'Block' = ('fork' : 'Tagged' 'Blocks') ∪ ('plain' : 'Tagged' 'PlainBlock') ∪ ('bare' : 'Paragraph')
 
 There are three kinds of block:
 
@@ -57,7 +57,7 @@
     * 'Tagged' 'PlainBlock' = ('tag' : 'Tag') × ('content' : 'PlainBlock')
     * 'PlainBlock' = ('contents' : 'Fragment') × ('annotation' : 'Annotation')
 
-- /Paragraphs/ contain inline content.
+- /Bare/ blocks (paragraphs) contain inline content.
 
     * 'Paragraph' = ('contents' : 'Line') × ('annotation' : 'Annotation')
 
@@ -72,9 +72,9 @@
 
 The Block type can be described in terms of BlockTag as:
 
-- 'Block' = ('blockTag' : 'BlockTag') ∪ ('paragraph' : 'Paragraph')
+- 'Block' = ('tagged' : 'BlockTag') ∪ ('bare' : 'Paragraph')
 
-Example: @'blockTag' % 'Optics.Core.filtered' (\x -> 'Optics.Core.view' 'name' x == "h1")@ is an affine fold that targets blocks with a tag name of "h1".
+Example: @'tagged' % 'Optics.Core.filtered' (\x -> 'Optics.Core.view' 'name' x == "h1")@ is an affine fold that targets blocks with a tag name of "h1".
 
 The BlockTag type can also be described as:
 
@@ -88,17 +88,17 @@
 
 Inline content is grouped into lines; we specify no particular semantics of line breaks but suggest that a typical consumer of 'Lines' will fold them together with a single space character interspersed between the lines.
 
-- 'Inline' = ('fork' : 'Tagged' 'Lines') ∪ ('plain' : 'Fragment')
+- 'Inline' = ('fork' or 'tagged' : 'Tagged' 'Lines') ∪ ('plain' or 'bare' : 'Fragment')
 
 There are two kinds of inline:
 
-- /Fork/ inlines contain more inlines.
+- /Fork/ or /tag/ inlines contain more inlines.
 
     * 'Tagged' 'Lines' = ('tag' : 'Tag') × ('content' : 'Lines')
     * 'Lines' = ('contents' : 'Line')
     * 'Line' = ('content' : 'Seq' 'Inline') × ('annotation' : 'Annotation')
 
-- /Plain/ inlines contain text.
+- /Plain/ or /bare/ inlines contain text.
 
 Unenforced guideline: Each 'Line' should contain at least one 'Inline'.
 
@@ -160,29 +160,40 @@
 'HasContent' and 'HasContents' have type aliases 'HasContents'' and 'HasContents'' respectively for types that only support simple optics.
 
 
-=== Fork and plain
+=== Tagged or bare
 
+At both the block and inline level, a node is either /tagged/ or /bare/, a fact manifested by the 'taggedOrBare' isomorphism of the 'IsTaggedOrBare' class.
+
+The 'tagged' prism is overloaded via the 'TaggedType' type family, and the 'bare' prism is overloaded via the 'BareType' family.
+
+List of nodes and their tagged/bare types:
+
++-----------------------+-----------------------+-----------------------+
+| __x__                 | __TaggedType x__      | __BareType x__        |
++-----------------------+-----------------------+-----------------------+
+| 'Block'               | 'BlockTag'            | 'Paragraph'           |
++-----------------------+-----------------------+-----------------------+
+| 'Inline'              | 'Tagged' 'Lines'      | 'Fragment'            |
++-----------------------+-----------------------+-----------------------+
+
+
+=== Fork or plain
+
 At both the block and inline level, a node may be a /fork/ that contains a sequence of more content at the same level, and a node may be /plain/ node that just contains text.
 
-The 'fork' prism is overloaded via the 'Fork' type family and 'CanFork' class. List of nodes and their fork types:
+The 'fork' prism is overloaded via the 'Fork' type family and 'CanFork' class.
 
-+-----------------------+-----------------------+
-| __x__                 | __Fork x__            |
-+-----------------------+-----------------------+
-| 'Block'               | 'Tagged' 'Blocks'     |
-+-----------------------+-----------------------+
-| 'Inline'              | 'Tagged' 'Lines'      |
-+-----------------------+-----------------------+
+The 'plain' prism is overloaded via the 'Plain' type family and 'CanBePlain' class.
 
-The 'plain' prism is overloaded via the 'Plain' type family and 'CanBePlain' class. List of nodes and their plain types:
+List of nodes and their fork/plain types:
 
-+-----------------------+-----------------------+
-| __x__                 | __Plain x__           |
-+-----------------------+-----------------------+
-| 'Block'               | 'Tagged' 'PlainBlock' |
-+-----------------------+-----------------------+
-| 'Inline'              | 'Fragment'            |
-+-----------------------+-----------------------+
++-----------------------+-----------------------+-----------------------+
+| __x__                 | __Fork x__            | __Plain x__           |
++-----------------------+-----------------------+-----------------------+
+| 'Block'               | 'Tagged' 'Blocks'     | 'Tagged' 'PlainBlock' |
++-----------------------+-----------------------+-----------------------+
+| 'Inline'              | 'Tagged' 'Lines'      | 'Fragment'            |
++-----------------------+-----------------------+-----------------------+
 
 ('Block' also has a third prism, 'paragraph', which is neither fork nor plain.)
 
@@ -239,6 +250,7 @@
     {- * Prisms -}
     {- ** Plain -} Plain, CanBePlain (..),
     {- ** Fork -} Fork, CanFork (..),
+    {- ** Tagged/bare -} tagged, bare, IsTaggedOrBare (..), TaggedOrBare (..),
     {- ** Paragraph -} paragraph,
 
     {- * Metadata -} Metadata (..), HasMetadata (..), HasManyMetadata (..),
diff --git a/library/pro-abstract/ProAbstract/Classes.hs b/library/pro-abstract/ProAbstract/Classes.hs
--- a/library/pro-abstract/ProAbstract/Classes.hs
+++ b/library/pro-abstract/ProAbstract/Classes.hs
@@ -1,7 +1,7 @@
 module ProAbstract.Classes
     (
-    -- * Block and inline prisms
-      CanBePlain (..), CanFork (..)
+    -- * Block and inline choices
+      CanBePlain (..), CanFork (..), IsTaggedOrBare (..)
 
     -- * Plaintext traversals
     , HasManyPlainBlocks (..), HasManyPlainInlines (..)
diff --git a/library/pro-abstract/ProAbstract/Datatypes.hs b/library/pro-abstract/ProAbstract/Datatypes.hs
--- a/library/pro-abstract/ProAbstract/Datatypes.hs
+++ b/library/pro-abstract/ProAbstract/Datatypes.hs
@@ -10,7 +10,7 @@
     , Inline (..), Line (..), Lines (..)
 
     -- * Tags and tagged things
-    , Tag (..), Tagged (..), BlockTag (..)
+    , Tag (..), Tagged (..), BlockTag (..), TaggedOrBare (..)
 
     -- * Paragraph
     , Paragraph (..)
diff --git a/library/pro-abstract/ProAbstract/Families.hs b/library/pro-abstract/ProAbstract/Families.hs
--- a/library/pro-abstract/ProAbstract/Families.hs
+++ b/library/pro-abstract/ProAbstract/Families.hs
@@ -1,10 +1,20 @@
 module ProAbstract.Families
-    ( Annotation
-    , Content
-    , Contents
-    , Fork
-    , Plain
+    (
+    -- * Annotation
+      Annotation
+
+    -- * Content plus a tag
     , Tagged
+
+    -- ** Content
+    , Content, Contents
+
+    -- * Fork or plain
+    , Fork, Plain
+
+    -- * Tagged or bare
+    , TaggedType, BareType
+
     ) where
 
 import ProAbstract.Annotation
diff --git a/library/pro-abstract/ProAbstract/Optics.hs b/library/pro-abstract/ProAbstract/Optics.hs
--- a/library/pro-abstract/ProAbstract/Optics.hs
+++ b/library/pro-abstract/ProAbstract/Optics.hs
@@ -10,7 +10,10 @@
     , metadata, atSetting, hasProperty, properties, settings
 
     -- * Prisms
-    , fork, plain, paragraph, blockTag
+    , fork, plain, paragraph, blockTag, tagged, bare
+
+    -- * Isomorphisms
+    , taggedOrBare
 
     -- * Traversals
     , allParagraphs, allPlainBlocks, allPlainInlines
diff --git a/library/pro-abstract/ProAbstract/Structure.hs b/library/pro-abstract/ProAbstract/Structure.hs
--- a/library/pro-abstract/ProAbstract/Structure.hs
+++ b/library/pro-abstract/ProAbstract/Structure.hs
@@ -18,9 +18,12 @@
     -- * Text
     , PlainBlock (..), Fragment (..)
 
-    -- * Plain and fork
+    -- * Plain or fork
     , CanBePlain (..), Plain, CanFork (..), Fork
 
+    -- * Tagged or bare
+    , IsTaggedOrBare (..), TaggedOrBare (..), tagged, bare
+
     -- * Traversals
     , HasManyParagraphs (..), HasManyPlainBlocks (..), HasManyPlainInlines (..)
 
@@ -39,6 +42,7 @@
 import ProAbstract.Structure.HasManyPlainBlocks
 import ProAbstract.Structure.HasManyPlainInlines
 import ProAbstract.Structure.Inline
+import ProAbstract.Structure.IsTaggedOrBare
 import ProAbstract.Structure.Paragraph
 import ProAbstract.Structure.Plain
 import ProAbstract.Structure.PlainBlock
diff --git a/library/pro-abstract/ProAbstract/Structure/IsTaggedOrBare.hs b/library/pro-abstract/ProAbstract/Structure/IsTaggedOrBare.hs
new file mode 100644
--- /dev/null
+++ b/library/pro-abstract/ProAbstract/Structure/IsTaggedOrBare.hs
@@ -0,0 +1,78 @@
+module ProAbstract.Structure.IsTaggedOrBare
+    ( TaggedOrBare (..)
+    , IsTaggedOrBare (..)
+    , tagged, bare
+    ) where
+
+import ProAbstract.Structure.Block
+import ProAbstract.Structure.BlockTag
+import ProAbstract.Structure.Fragment
+import ProAbstract.Structure.Inline
+import ProAbstract.Structure.Paragraph
+
+data TaggedOrBare a =
+    IsTagged (TaggedType a)
+  | IsBare (BareType a)
+
+tagged' :: Prism' (TaggedOrBare a) (TaggedType a)
+tagged' = prism' IsTagged \case{ IsTagged x -> Just x; _ -> Nothing }
+
+bare' :: Prism' (TaggedOrBare a) (BareType a)
+bare' = prism' IsBare \case{ IsBare x -> Just x; _ -> Nothing }
+
+class IsTaggedOrBare a where
+
+    type TaggedType a
+    type BareType a
+
+    taggedOrBare :: Iso' a (TaggedOrBare a)
+
+tagged :: IsTaggedOrBare a => Prism' a (TaggedType a)
+tagged = taggedOrBare % tagged'
+
+bare :: IsTaggedOrBare a => Prism' a (BareType a)
+bare = taggedOrBare % bare'
+
+instance IsTaggedOrBare (TaggedOrBare a) where
+
+    type TaggedType (TaggedOrBare a) = TaggedType a
+    type BareType (TaggedOrBare a) = BareType a
+
+    taggedOrBare = iso f g
+      where
+        f = \case
+            IsTagged x -> IsTagged x
+            IsBare x -> IsBare x
+        g = \case
+            IsTagged x -> IsTagged x
+            IsBare x -> IsBare x
+
+instance IsTaggedOrBare (Inline ann) where
+
+    type TaggedType (Inline ann) = Tagged (Lines ann)
+    type BareType (Inline ann) = Fragment ann
+
+    taggedOrBare = iso f g
+      where
+        f = \case
+            InlineFork x -> IsTagged x
+            InlinePlain x -> IsBare x
+        g = \case
+            IsTagged x -> InlineFork x
+            IsBare x -> InlinePlain x
+
+instance IsTaggedOrBare (Block ann) where
+
+    type TaggedType (Block ann) = BlockTag ann
+    type BareType (Block ann) = Paragraph ann
+
+    taggedOrBare = iso f g
+      where
+        f = \case
+            BlockPlain x -> IsTagged (BlockTagPlain x)
+            BlockFork x -> IsTagged (BlockTagFork x)
+            BlockParagraph x -> IsBare x
+        g = \case
+            IsTagged (BlockTagPlain x) -> BlockPlain x
+            IsTagged (BlockTagFork x) -> BlockFork x
+            IsBare x -> BlockParagraph x
diff --git a/library/pro-abstract/ProAbstract/Types.hs b/library/pro-abstract/ProAbstract/Types.hs
--- a/library/pro-abstract/ProAbstract/Types.hs
+++ b/library/pro-abstract/ProAbstract/Types.hs
@@ -21,6 +21,7 @@
     , Set
     , Tag
     , Tagged
+    , TaggedOrBare
     , Text
     ) where
 
diff --git a/pro-abstract.cabal b/pro-abstract.cabal
--- a/pro-abstract.cabal
+++ b/pro-abstract.cabal
@@ -1,7 +1,7 @@
 cabal-version: 3.0
 
 name: pro-abstract
-version: 0.1.2.0
+version: 0.1.3.0
 
 category: Language
 synopsis: Abstract syntax for writing documents
@@ -100,6 +100,7 @@
       , ProAbstract.Structure.HasManyPlainBlocks
       , ProAbstract.Structure.HasManyPlainInlines
       , ProAbstract.Structure.Inline
+      , ProAbstract.Structure.IsTaggedOrBare
       , ProAbstract.Structure.Paragraph
       , ProAbstract.Structure.Plain
       , ProAbstract.Structure.PlainBlock