diff --git a/modflow_devtools/dfn.py b/modflow_devtools/dfn.py
index 4d8c70a0..33bcc14a 100644
--- a/modflow_devtools/dfn.py
+++ b/modflow_devtools/dfn.py
@@ -25,24 +25,10 @@
 from boltons.iterutils import remap
 
 from modflow_devtools.download import download_and_unzip
+from modflow_devtools.misc import try_literal_eval
 
-# TODO: use dataclasses instead of typed dicts? static
-# methods on typed dicts are evidently not allowed
-# mypy: ignore-errors
 
-
-def _try_literal_eval(value: str) -> Any:
-    """
-    Try to parse a string as a literal. If this fails,
-    return the value unaltered.
-    """
-    try:
-        return literal_eval(value)
-    except (SyntaxError, ValueError):
-        return value
-
-
-def _try_parse_bool(value: Any) -> Any:
+def try_parse_bool(value: Any) -> Any:
     """
     Try to parse a boolean from a string as represented
     in a DFN file, otherwise return the value unaltered.
@@ -54,7 +40,7 @@ def _try_parse_bool(value: Any) -> Any:
     return value
 
 
-def _field_attr_sort_key(item) -> int:
+def field_attr_sort_key(item) -> int:
     """
     Sort key for input field attributes. The order is:
     -1. block
@@ -90,6 +76,22 @@ def _field_attr_sort_key(item) -> int:
     return 8
 
 
+def block_sort_key(item) -> int:
+    k, _ = item
+    if k == "options":
+        return 0
+    elif k == "dimensions":
+        return 1
+    elif k == "griddata":
+        return 2
+    elif k == "packagedata":
+        return 3
+    elif "period" in k:
+        return 4
+    else:
+        return 5
+
+
 FormatVersion = Literal[1, 2]
 """DFN format version number."""
 
@@ -113,11 +115,26 @@ def _field_attr_sort_key(item) -> int:
 ]
 
 
-_SCALAR_TYPES = FieldType.__args__[:4]
+_SCALAR_TYPES = ("keyword", "integer", "double precision", "string")
 
 
 Dfns = dict[str, "Dfn"]
 Fields = dict[str, "Field"]
+Block = Fields
+Blocks = dict[str, Block]
+
+
+def get_blocks(dfn: "Dfn") -> Blocks:
+    """
+    Extract blocks from an input definition. Any entry whose key
+    is not explicitly defined in `Dfn` is a block.
+    """
+    return dict(
+        sorted(
+            {k: v for k, v in dfn.items() if k not in Dfn.__annotations__}.items(),  # type: ignore
+            key=block_sort_key,
+        )
+    )
 
 
 class Field(TypedDict):
@@ -125,12 +142,12 @@ class Field(TypedDict):
 
     name: str
     type: FieldType
-    shape: Any | None = None
-    block: str | None = None
-    default: Any | None = None
-    children: Optional["Fields"] = None
-    description: str | None = None
-    reader: Reader = "urword"
+    shape: Any | None
+    block: str | None
+    default: Any | None
+    children: Optional["Fields"]
+    description: str | None
+    reader: Reader
 
 
 class Ref(TypedDict):
@@ -188,14 +205,14 @@ class Dfn(TypedDict):
     """
 
     name: str
-    advanced: bool = False
-    multi: bool = False
-    parent: str | None = None
-    ref: Ref | None = None
-    sln: Sln | None = None
-    fkeys: Dfns | None = None
-
-    @staticmethod
+    advanced: bool
+    multi: bool
+    parent: str | None
+    ref: Ref | None
+    sln: Sln | None
+    fkeys: Dfns | None
+
+    @staticmethod  # type: ignore[misc]
     def _load_v1_flat(f, common: dict | None = None) -> tuple[Mapping, list[str]]:
         field = {}
         flat = []
@@ -269,7 +286,7 @@ def _load_v1_flat(f, common: dict | None = None) -> tuple[Mapping, list[str]]:
         # the point of the OMD is to losslessly handle duplicate variable names
         return OMD(flat), meta
 
-    @classmethod
+    @classmethod  # type: ignore[misc]
     def _load_v1(cls, f, name, **kwargs) -> "Dfn":
         """
         Temporary load routine for the v1 DFN format.
@@ -279,6 +296,41 @@ def _load_v1(cls, f, name, **kwargs) -> "Dfn":
         refs = kwargs.pop("refs", {})
         flat, meta = Dfn._load_v1_flat(f, **kwargs)
 
+        def _convert_period_block(block: Block) -> Block:
+            """
+            Convert a period block recarray to individual arrays, one per column.
+
+            Extracts recarray fields and creates separate array variables. Gives
+            each an appropriate grid- or tdis-aligned shape as opposed to sparse
+            list shape in terms of maxbound as previously.
+            """
+
+            fields = list(block.values())
+            if fields[0]["type"] == "recarray":
+                assert len(fields) == 1
+                recarray_name = fields[0]["name"]
+                item = next(iter(fields[0]["children"].values()))
+                columns = item["children"]
+            else:
+                recarray_name = None
+                columns = block
+            block.pop(recarray_name, None)
+            cellid = columns.pop("cellid", None)
+            for col_name, column in columns.items():
+                col_copy = column.copy()
+                old_dims = col_copy.get("shape")
+                if old_dims:
+                    old_dims = old_dims[1:-1].split(",")
+                new_dims = ["nper"]
+                if cellid:
+                    new_dims.append("nnodes")
+                if old_dims:
+                    new_dims.extend([dim for dim in old_dims if dim != "maxbound"])
+                col_copy["shape"] = f"({', '.join(new_dims)})"
+                block[col_name] = col_copy
+
+            return block
+
         def _convert_field(var: dict[str, Any]) -> Field:
             """
             Convert an input field specification from its representation
@@ -300,7 +352,7 @@ def _load(field) -> Field:
                 # stay a string except default values, which we'll
                 # try to parse as arbitrary literals below, and at
                 # some point types, once we introduce type hinting
-                field = {k: _try_parse_bool(v) for k, v in field.items()}
+                field = {k: try_parse_bool(v) for k, v in field.items()}
 
                 _name = field.pop("name")
                 _type = field.pop("type", None)
@@ -308,7 +360,7 @@ def _load(field) -> Field:
                 shape = None if shape == "" else shape
                 block = field.pop("block", None)
                 default = field.pop("default", None)
-                default = _try_literal_eval(default) if _type != "string" else default
+                default = try_literal_eval(default) if _type != "string" else default
                 description = field.pop("description", "")
                 reader = field.pop("reader", "urword")
                 ref = refs.get(_name, None)
@@ -343,7 +395,7 @@ def _item() -> Field:
                             name=_name,
                             type="record",
                             block=block,
-                            fields=_fields(),
+                            children=_fields(),
                             description=description.replace(
                                 "is the list of", "is the record of"
                             ),
@@ -368,7 +420,7 @@ def _item() -> Field:
                         name=first["name"] if single else _name,
                         type=item_type,
                         block=block,
-                        fields=first["fields"] if single else fields,
+                        children=first["children"] if single else fields,
                         description=description.replace(
                             "is the list of", f"is the {item_type} of"
                         ),
@@ -411,15 +463,16 @@ def _fields() -> Fields:
                 )
 
                 if _type.startswith("recarray"):
-                    var_["item"] = _item()
+                    item = _item()
+                    var_["children"] = {item["name"]: item}
                     var_["type"] = "recarray"
 
                 elif _type.startswith("keystring"):
-                    var_["choices"] = _choices()
+                    var_["children"] = _choices()
                     var_["type"] = "keystring"
 
                 elif _type.startswith("record"):
-                    var_["fields"] = _fields()
+                    var_["children"] = _fields()
                     var_["type"] = "record"
 
                 # for now, we can tell a var is an array if its type
@@ -453,7 +506,7 @@ def _fields() -> Fields:
 
                 return var_
 
-            return dict(sorted(_load(var).items(), key=_field_attr_sort_key))
+            return dict(sorted(_load(var).items(), key=field_attr_sort_key))
 
         # load top-level fields. any nested
         # fields will be loaded recursively
@@ -469,11 +522,10 @@ def _fields() -> Fields:
             for block_name, block in groupby(fields.values(), lambda v: v["block"])
         }
 
-        # mark transient blocks
-        transient_index_vars = flat.getlist("iper")
-        for transient_index in transient_index_vars:
-            transient_block = transient_index["block"]
-            blocks[transient_block]["transient_block"] = True
+        # if there's a period block, extract distinct arrays from
+        # the recarray-style definition
+        if (period_block := blocks.get("period", None)) is not None:
+            blocks["period"] = _convert_period_block(period_block)
 
         # remove unneeded variable attributes
         def remove_attrs(path, key, value):
@@ -559,14 +611,14 @@ def _rest():
             **blocks,
         )
 
-    @classmethod
+    @classmethod  # type: ignore[misc]
     def _load_v2(cls, f, name) -> "Dfn":
         data = tomli.load(f)
         if name and name != data.get("name", None):
             raise ValueError(f"Name mismatch, expected {name}")
         return cls(**data)
 
-    @classmethod
+    @classmethod  # type: ignore[misc]
     def load(
         cls,
         f,
@@ -585,7 +637,7 @@ def load(
         else:
             raise ValueError(f"Unsupported version, expected one of {version.__args__}")
 
-    @staticmethod
+    @staticmethod  # type: ignore[misc]
     def _load_all_v1(dfndir: PathLike) -> Dfns:
         paths: list[Path] = [
             p for p in dfndir.glob("*.dfn") if p.stem not in ["common", "flopy"]
@@ -617,7 +669,7 @@ def _load_all_v1(dfndir: PathLike) -> Dfns:
 
         return dfns
 
-    @staticmethod
+    @staticmethod  # type: ignore[misc]
     def _load_all_v2(dfndir: PathLike) -> Dfns:
         paths: list[Path] = [
             p for p in dfndir.glob("*.toml") if p.stem not in ["common", "flopy"]
@@ -630,7 +682,7 @@ def _load_all_v2(dfndir: PathLike) -> Dfns:
 
         return dfns
 
-    @staticmethod
+    @staticmethod  # type: ignore[misc]
     def load_all(dfndir: PathLike, version: FormatVersion = 1) -> Dfns:
         """Load all component definitions from the given directory."""
         if version == 1:
@@ -640,7 +692,7 @@ def load_all(dfndir: PathLike, version: FormatVersion = 1) -> Dfns:
         else:
             raise ValueError(f"Unsupported version, expected one of {version.__args__}")
 
-    @staticmethod
+    @staticmethod  # type: ignore[misc]
     def load_tree(dfndir: PathLike, version: FormatVersion = 2) -> dict:
         """Load all definitions and return as hierarchical tree."""
         dfns = Dfn.load_all(dfndir, version)
@@ -664,8 +716,8 @@ def infer_tree(dfns: dict[str, Dfn]) -> dict:
     if root_name != "sim":
         raise ValueError(f"Root component must be named 'sim', found '{root_name}'")
 
-    def add_children(node_name: str) -> dict:
-        node = dfns[node_name].copy()
+    def add_children(node_name: str) -> dict[str, Any]:
+        node = dict(dfns[node_name])
         children = [
             name for name, dfn in dfns.items() if dfn.get("parent") == node_name
         ]
@@ -684,7 +736,7 @@ def get_dfns(
     if verbose:
         print(f"Downloading MODFLOW 6 repository from {url}")
     with tempfile.TemporaryDirectory() as tmp:
-        dl_path = download_and_unzip(url, tmp, verbose=verbose)
+        dl_path = download_and_unzip(url, Path(tmp), verbose=verbose)
         contents = list(dl_path.glob("modflow6-*"))
         proj_path = next(iter(contents), None)
         if not proj_path:
diff --git a/modflow_devtools/misc.py b/modflow_devtools/misc.py
index e9d40929..65bf614b 100644
--- a/modflow_devtools/misc.py
+++ b/modflow_devtools/misc.py
@@ -565,3 +565,19 @@ def try_get_enum_value(v: Any) -> Any:
     of an enumeration, otherwise return it unaltered.
     """
     return v.value if isinstance(v, Enum) else v
+
+
+# TODO: use dataclasses instead of typed dicts? static
+# methods on typed dicts are evidently not allowed
+# mypy: ignore-errors
+
+
+def try_literal_eval(value: str) -> Any:
+    """
+    Try to parse a string as a literal. If this fails,
+    return the value unaltered.
+    """
+    try:
+        return literal_eval(value)
+    except (SyntaxError, ValueError):
+        return value