diff --git a/c/containers/Makefile.am b/c/containers/Makefile.am
index 234e48474..ae0b1036f 100644
--- a/c/containers/Makefile.am
+++ b/c/containers/Makefile.am
@@ -1,5 +1,7 @@
 noinst_LTLIBRARIES=	libcontainers.la
 libcontainers_la_SOURCES=	\
+			bind_stack.c \
+			bind_stack.h \
 			dheap.c \
 			dheap.h \
 			dvector.c \
diff --git a/c/containers/bind_stack.c b/c/containers/bind_stack.c
new file mode 100644
index 000000000..0abb177a5
--- /dev/null
+++ b/c/containers/bind_stack.c
@@ -0,0 +1,21 @@
+#include <stdlib.h>
+#include "lib/mlrutil.h"
+#include "lib/mlr_globals.h"
+#include "containers/bind_stack.h"
+
+bind_stack_t* bind_stack_alloc() {
+	return NULL; // xxx stub
+}
+
+void bind_stack_free(bind_stack_t* pstack) {
+}
+
+void bind_stack_push(bind_stack_t* pstack, mlhmmv_t* pframe) {
+}
+
+void bind_stack_pop(bind_stack_t* pstack) {
+}
+
+mv_t* bind_stack_resolve(bind_stack_t* pstack, char* key) {
+	return NULL; // xxx stub
+}
diff --git a/c/containers/bind_stack.h b/c/containers/bind_stack.h
new file mode 100644
index 000000000..2259c8dcd
--- /dev/null
+++ b/c/containers/bind_stack.h
@@ -0,0 +1,18 @@
+#ifndef BIND_STACK_H
+#define BIND_STACK_H
+
+#include "containers/mlrval.h"
+#include "containers/mlhmmv.h"
+
+// Bound & scoped variables for use in for-loops.
+typedef struct _bind_stack_t {
+} bind_stack_t;
+
+bind_stack_t* bind_stack_alloc();
+void bind_stack_free(bind_stack_t* pstack);
+
+void bind_stack_push(bind_stack_t* pstack, mlhmmv_t* pframe);
+void bind_stack_pop(bind_stack_t* pstack);
+mv_t* bind_stack_resolve(bind_stack_t* pstack, char* key);
+
+#endif // BIND_STACK_H
diff --git a/c/todo.txt b/c/todo.txt
index 3ee06c852..53a9f057f 100644
--- a/c/todo.txt
+++ b/c/todo.txt
@@ -6,8 +6,16 @@ BUGFIXES
 ================================================================
 TOP-OF-LIST SUMMARY
 
-! need evaluators (new context mllhmv) for boundvars.
-! need $[k] and @[k].
+* for:
+  - bindstack container
+  - boundvar evaluators @ rval: pass in a bindstack. *for miller* it ought to be possible
+    to be better at nested-scope name resolution than stack backwalks w/ hashgets at each
+    step. at each level a name will have one nearest at-or-up binding or none at all.
+  -> hide that in the blackboxed bindstack.
+  - $[boundvar] and @[boundvar] evaluators.
+  - cookbook example: key<->val inverter
+  - cookbook example: komosa originals x 2
+
 * for-variants:
   ?? take out the v part??
   * for (k, v in $*) { if (k =~ "^f.*$") { $sum += v} }
@@ -18,17 +26,10 @@ TOP-OF-LIST SUMMARY
   ? for (k1, k2, v in @v[]["a"][]) ? no -- easier to do this w/ cond-block @ 2nd loop
   ? for (k1, k2, v in @*)
   ? break/continue: fully support or eliminate from the lexer/parser
-* for:
-  - bindstack container
-  - boundvar evaluators @ rval: pass in a bindstack. *for miller* it ought to be possible
-    to be better at nested-scope name resolution than stack backwalks w/ hashgets at each
-    step. at each level a name will have one nearest at-or-up binding or none at all.
-  -> hide that in the blackboxed bindstack.
-  - $[boundvar] and @[boundvar] evaluators.
-  - cookbook example: key<->val inverter
-  - cookbook example: komosa originals x 2
-* local vars w/ decl syntax
-* user-defined functions ... ??
+
+? local vars w/ decl syntax
+? user-defined functions ... ??
+
 * eliminate the need for semicolon after curly brace. for now, highlighted faqent.
 * cst-time parse validations: top-level-only begin/end (done); no $stuff at begin/end.
 ? triple-for with boundvars??