diff --git a/README.md b/README.md
index a2972fa..6c86fd2 100644
--- a/README.md
+++ b/README.md
@@ -967,7 +967,7 @@ node.go         the node model and JSON -> node compilation
 table.go        tables: their options, format and cells, the link to the parent beside them, and how a path passes and draws a table
 name.go         names: {x as n} bindings, the scopes they live in, the reads they answer, and what each resolves to at load: its target, its reads and the keys they address
 namefence.go    the load fences over names
-pick.go         a render's named picks: the frames of the name scopes rendering, the memo a pick keeps, and the reads kept under it
+pick.go         a render's named picks: the frame of each name scope rendering, the memo a pick keeps, and the reads kept under it
 env.go          renderEnv: what a render reads names and rows through, the stack of frames it renders in, and the frames a read opens and finds
 path.go         the dotted-path walks, and proving a path reaches a node
 render.go       Fake, the recursive renderer (choices, format strings, expansions) and the reads its tokens make
@@ -981,7 +981,7 @@ resolve.go      resolving templates against the assembled tree in steps, each ov
 graph.go        the node graph: tree walks, containment and render edges, and the cycle and repeat fences
 sorted.go       sortedNames: a map's keys, sorted
 calc.go         the {calc()} operand checks: never a number, and a constant zero divisor
-datatype.go     column datatypes: DataType, where datatype and null may sit, a column's datatype
+datatype.go     column datatypes: DataType, a template's declared datatype, a column's datatype
 valueproof.go   the value proof: what a typed column, calc operand or struct field holds, checked at load
 data.go         the load path: the categories internal/datafiles hands over, compiled into one merged tree, and the load pipeline every entry point runs
 cmd/fejkdata/   the fejkdata CLI
diff --git a/data-import/geo-se.py b/data-import/geo-se.py
index aa1619c..c3780e2 100644
--- a/data-import/geo-se.py
+++ b/data-import/geo-se.py
@@ -170,9 +170,7 @@ def streets(segments, codes, localities, per_locality):
 
 
 def main():
-    p = geo.parser(__doc__, "SE")
-    p.add_argument("--key-file", help="file holding the Trafikverket API key; TRAFIKVERKET_API_KEY otherwise")
-    a = p.parse_args()
+    a = geo.parser(__doc__, "SE", key_file={"help": "file holding the Trafikverket API key; TRAFIKVERKET_API_KEY otherwise"}).parse_args()
     key = Path(a.key_file).read_text().strip() if a.key_file else os.environ.get("TRAFIKVERKET_API_KEY")
     if not key:
         sys.exit("set TRAFIKVERKET_API_KEY or pass --key-file")
diff --git a/data-import/geo-us.py b/data-import/geo-us.py
index b2db9ab..7b7297d 100644
--- a/data-import/geo-us.py
+++ b/data-import/geo-us.py
@@ -154,9 +154,7 @@ def streets(cache, counties, locality_of_zcta, per_locality):
 
 
 def main():
-    p = geo.parser(__doc__, "US")
-    p.add_argument("--min-population", type=int, default=25000)
-    a = p.parse_args()
+    a = geo.parser(__doc__, "US", min_population={"type": int, "default": 25000}).parse_args()
     cache, out = geo.directories(a)
 
     state_population = {r["STATE"]: r[ESTIMATE] for r in csv_rows(cache, STATES, "nst-est2025.csv") if r["SUMLEV"] == "040"}
diff --git a/data-import/geo.py b/data-import/geo.py
index 7f743b5..fc25f92 100644
--- a/data-import/geo.py
+++ b/data-import/geo.py
@@ -1,4 +1,4 @@
-"""The steps every country's geo import takes."""
+"""The steps a country's geo import may share with another's."""
 import argparse
 import collections
 import math
@@ -9,12 +9,12 @@ DATA = Path(__file__).resolve().parent.parent / "data" / "geo"
 CACHE = Path(__file__).resolve().parent / "cache"
 
 
-def parser(doc, country):
-    """The options every country's import takes; a script adds its own before parse_args."""
+def parser(doc, country, **own):
+    """The options every country's import takes and the script's own, keyed by name with "_" for "-", in name order."""
+    options = {"cache": {"default": str(CACHE)}, "out": {"default": str(DATA / country)}, "streets_per_locality": {"type": int, "default": 10}, **own}
     p = argparse.ArgumentParser(description=doc.splitlines()[0])
-    p.add_argument("--cache", default=str(CACHE))
-    p.add_argument("--out", default=str(DATA / country))
-    p.add_argument("--streets-per-locality", type=int, default=10)
+    for name in sorted(options):
+        p.add_argument("--" + name.replace("_", "-"), **options[name])
     return p
 
 
diff --git a/datatype.go b/datatype.go
index d22b316..fcd549f 100644
--- a/datatype.go
+++ b/datatype.go
@@ -156,7 +156,7 @@ func disagreement(a *template, da DataType, b *template, db DataType) error {
 	}
 	message, ok := disagreements[[2]itemKind{kindOf(c.fix), kindOf(c.other)}]
 	if !ok {
-		panic(invariant.Broken("two text items hold one datatype, so they never disagree"))
+		panic(invariant.Broken("disagreement has no message for item kinds %d and %d; two text items hold one datatype, so they never disagree", kindOf(c.fix), kindOf(c.other)))
 	}
 	return message(c)
 }
diff --git a/table.go b/table.go
index 7459202..56b4202 100644
--- a/table.go
+++ b/table.go
@@ -246,7 +246,7 @@ type tableRoute struct {
 }
 
 // route is how tail passes t. fromRow means the previous route stepped into t
-// from a row of an ancestor table, so t reads a row even where tail is empty; a
+// from a row of a table linked to it, so t reads a row even where tail is empty; a
 // table reached otherwise, with no selector and an empty tail, is left to a render's
 // own draw.
 func (t *table) route(tail []string, fromRow bool) (tableRoute, error) {