diff --git a/README.md b/README.md
index 649cf70..14c4145 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@ are regenerated on each release — patches cannot be merged directly.
 Report problems (or send patches) to the author; accepted changes are
 applied to the development tree and appear in a following snapshot.
 
-This snapshot was assembled from development commit `bc7cd62b6f68`.
+This snapshot was assembled from development commit `6024f49c2859`.
 
 ## License
 
diff --git a/mac/argtype.cpp b/mac/argtype.cpp
index f930ba2..877e373 100644
--- a/mac/argtype.cpp
+++ b/mac/argtype.cpp
@@ -7,13 +7,15 @@
 #include "util.h"
 
 Argtype::Argtype(std::string name, std::string desc, std::string symbolic_pattern, std::string pattern,
-                 std::string default_value, std::string python_cast, modify_string_f python_format,
+                 std::string default_value, std::string alone_value,
+                 std::string python_cast, modify_string_f python_format,
                  const Locator& loc)
     : m_name(name)
     , m_desc(desc)
     , m_symbolic_pattern(symbolic_pattern)
     , m_pattern(pattern)
     , m_default(default_value)
+    , m_alone(alone_value)
     , m_python_cast(python_cast)
     , m_python_format(python_format)
     , m_regex(std::regex(pattern))
diff --git a/mac/argtype.h b/mac/argtype.h
index 8e77360..00e5913 100644
--- a/mac/argtype.h
+++ b/mac/argtype.h
@@ -26,7 +26,8 @@ public:
         {};
 
     Argtype(std::string name, std::string desc, std::string symbolic_pattern, std::string pattern,
-            std::string default_value, std::string python_cast, modify_string_f python_format,
+            std::string default_value, std::string alone_value,
+            std::string python_cast, modify_string_f python_format,
             const Locator& loc);
 
     std::string python_value(const std::string& var_name, std::vector<std::string> value, size_t name_size);
@@ -48,6 +49,18 @@ public:
     // (cell_hpos, column_width); general types (bool, float) have no
     // sensible universal default and leave it empty.
     std::string m_default {};
+    // Value for an optional argument whose name is written alone, with no
+    // value after it (:number rather than :number 10).  Declared by the
+    // argument type, never by a klammer's parameter declaration: the
+    // default is what a klammer means by silence and is properly
+    // per-klammer, but a bare option name must read the same way in every
+    // klammer or the writer cannot know what it means without consulting
+    // each signature.  bool declares "true", which is where the
+    // presence-means-true convention comes from; a type whose pattern
+    // matches everything cannot declare it (the value would swallow the
+    // following text instead).  Empty means the type has no alone value,
+    // and a bare option name yields the empty string as before.
+    std::string m_alone {};
     // Type parameter for parameterized types like rest(2): the value N
     // is bound around the python cast as (lambda N: <cast>)(2)(...).
     // Empty means unparameterized; a type with a default parameter
diff --git a/mac/argtype_set.cpp b/mac/argtype_set.cpp
index 7277c09..71d0afd 100644
--- a/mac/argtype_set.cpp
+++ b/mac/argtype_set.cpp
@@ -13,7 +13,7 @@
 
 Parameter_set& Argtype_set::parameters()
 {
-    static Parameter_set instance("name | desc :pattern .* :python_cast str :default");
+    static Parameter_set instance("name | desc :pattern .* :python_cast str :default :alone");
     return instance;
 }
 
@@ -22,11 +22,15 @@ Argtype_set::Argtype_set()
     (void)(void)K::log(2);
     Locator loc = current_locator();
     for (auto [name, desc, pattern, python_cast, python_format] : base_argtypes) {
-        add(name, desc, pattern, "", python_cast, python_format, loc);
+        add(name, desc, pattern, "", "", python_cast, python_format, loc);
     }
     // rest is a parameterized type (rest(N)); an unparameterized use is
     // one-dimensional.
     m_types["rest"].m_parameter = "1";
+    // A bool option written alone is true: :number means :number true.
+    // This is a declaration like any other type's :alone, not an engine
+    // special case for booleans.
+    m_types["bool"].m_alone = "true";
 }
 
 std::string Argtype_set::replace_symbols(const std::string& pattern, const Locator& loc)
@@ -63,6 +67,7 @@ void Argtype_set::check_for_existing_definition(
 
 void Argtype_set::add(const std::string& name, const std::string& desc,
                       const std::string& pattern, const std::string& default_value,
+                      const std::string& alone_value,
                       const std::string& python_cast, modify_string_f python_format,
                       const Locator& loc)
 {
@@ -73,7 +78,8 @@ void Argtype_set::add(const std::string& name, const std::string& desc,
     m_pattern_size = std::max(m_pattern_size, expanded_pattern.size());
     try {
         m_types[name] = Argtype(name, desc, pattern, expanded_pattern,
-                                default_value, python_cast, python_format, loc);
+                                default_value, alone_value,
+                                python_cast, python_format, loc);
     } catch (const std::regex_error& e) {
         std::stringstream ss {};
         ss << "The pattern for argument type \"" << name
@@ -92,6 +98,35 @@ void Argtype_set::add(const std::string& name, const std::string& desc,
            << "  " << pattern << "\n";
         throw Definition_error(ss.str(), loc, false);
     }
+    if (!alone_value.empty()) {
+        // A pattern that matches running text cannot delimit a bare option
+        // name from the text after it: an option's value runs to the next
+        // bar or option name, so ":opt some words" would silently take
+        // "some words" as the value and the alone value would never be
+        // reached.  A pattern that rejects multi-word text raises a clean
+        // argument error there instead.  The test is behavioral rather
+        // than a comparison against matches_all()'s one literal pattern,
+        // because an @@@argtype written without a :pattern gets ".*",
+        // which is equally unable to delimit.
+        if (std::regex_match(std::string("one two"), m_types[name].m_regex)) {
+            std::stringstream ss {};
+            ss << "The argument type \"" << name << "\" cannot declare an :alone value "
+               << "because its pattern matches running text:\n"
+               << "  " << pattern << "\n\n"
+               << "An :alone value is used when an option name is written without a "
+               << "value.  A type that matches running text cannot tell a bare option "
+               << "name from one whose value follows it, so the text after the name "
+               << "would be taken as the value instead.\n";
+            throw Definition_error(ss.str(), loc, false);
+        }
+        if (!std::regex_match(alone_value, m_types[name].m_regex)) {
+            std::stringstream ss {};
+            ss << "The alone value \"" << alone_value << "\" for argument type \""
+               << name << "\" does not match its own pattern:\n"
+               << "  " << pattern << "\n";
+            throw Definition_error(ss.str(), loc, false);
+        }
+    }
     m_names.push_back(name);
 }
 
@@ -108,7 +143,7 @@ void Argtype_set::add(std::vector<Katom>::iterator begin, std::vector<Katom>::it
     // std::for_each(begin, end+1, [](Katom& k) { k.m_type = katom_t::replaced; });
 
     add(values["name"], values["desc"], values["pattern"], values["default"],
-        values["python_cast"], modify_string_f{},
+        values["alone"], values["python_cast"], modify_string_f{},
         begin->m_loc);
     
     modify_type(katom_t::replaced, begin, end);
@@ -143,6 +178,21 @@ std::string Argtype_set::eval(
     }
 }
 
+// The values a type supplies when an argument does not give one: the
+// default (the option was not written at all) and the alone value (the
+// option name was written without a value).  Shown only when declared.
+static std::string values_note(const Argtype& type)
+{
+    std::stringstream note {};
+    if (!type.m_default.empty()) {
+        note << " [default: " << type.m_default << "]";
+    }
+    if (!type.m_alone.empty()) {
+        note << " [alone: " << type.m_alone << "]";
+    }
+    return note.str();
+}
+
 std::string Argtype_set::describe(bool long_form, int indent_width) const
 {
     std::string indent(' ', indent_width);
@@ -161,8 +211,9 @@ std::string Argtype_set::describe(bool long_form, int indent_width) const
                 result << sp_arrow << m_types.at(name).m_pattern;
             result << "\n";
         } else {
-            // result << abbrev(m_types.at(name).m_desc) << "\n";           
-            result << regex_split(m_types.at(name).m_desc, std::regex("\\n"), true)[0] << "\n";
+            // result << abbrev(m_types.at(name).m_desc) << "\n";
+            result << regex_split(m_types.at(name).m_desc, std::regex("\\n"), true)[0]
+                   << values_note(m_types.at(name)) << "\n";
         }
     }
     if (long_form) {
diff --git a/mac/argtype_set.h b/mac/argtype_set.h
index e0aed62..95954e9 100644
--- a/mac/argtype_set.h
+++ b/mac/argtype_set.h
@@ -19,6 +19,7 @@ public:
     void check_for_existing_definition(const std::string& name, const Locator& loc);
     void add(const std::string& name, const std::string& desc,
              const std::string& pattern, const std::string& default_value,
+             const std::string& alone_value,
              const std::string& python_cast, modify_string_f python_format,
              const Locator& loc);
     void add(std::vector<Katom>::iterator begin, std::vector<Katom>::iterator end, std::vector<Katom>& katoms);
diff --git a/mac/argument_set.cpp b/mac/argument_set.cpp
index 68b21aa..7d39234 100644
--- a/mac/argument_set.cpp
+++ b/mac/argument_set.cpp
@@ -417,6 +417,16 @@ Parameter_set::value_map(
     }
     auto optional_values = check_optional(optional, loc);
     for (auto [key, value] : optional_values) {
+        // check_optional returns only the options that were actually
+        // written, so an empty value here means the name was written alone
+        // (":number" rather than ":number 10") — distinct from the option
+        // being absent, which is filled from the default below.  The
+        // argument type supplies the alone value; bool declares "true",
+        // which is what makes a bare boolean option mean true.
+        const Parameter* parameter = find(key);
+        if (value.empty() && parameter && !parameter->m_argtype.m_alone.empty()) {
+            value = parameter->m_argtype.m_alone;
+        }
         values[key] = value;
     }
     for (auto opt : m_optional) {
diff --git a/sks/code/code.k b/sks/code/code.k
index ac6aaab..878c6c0 100644
--- a/sks/code/code.k
+++ b/sks/code/code.k
@@ -1,5 +1,5 @@
 
-@@code.k :filename :pattern :caption :number | text.literal :
+@@code.k :filename :pattern :caption :number.bool | text.literal :
 A source file displayed verbatim
 @@
 
diff --git a/sks/list/list.py b/sks/list/list.py
index 28710bf..96a8a60 100644
--- a/sks/list/list.py
+++ b/sks/list/list.py
@@ -158,7 +158,7 @@ def tex_list(K, list_type, items):
     body = "\n\n".join([f"\\item {e}" for e in items])
     command = {'ol' : 'enumerate', 'ul' : 'itemize'}[list_type]
     topsep = '[topsep=0pt]'
-    listsep = '\\setlist{nolistsep}' if K.cmp != 'false' else ''
+    listsep = '\\setlist{nolistsep}' if K.cmp else ''
     result = f'{listsep}\n\\begin{{{command}}}{topsep}\n{body}\n\\end{{{command}}}\n'
     return result
 
diff --git a/sks/table/table.k b/sks/table/table.k
index c58f209..73ba2fe 100644
--- a/sks/table/table.k
+++ b/sks/table/table.k
@@ -75,6 +75,7 @@
 
   :pattern ((?^:top^|head^|inner^|bottom^|all^|none)(?^:'index_subsets')?^|'indexed_range'^|\s+)+
   :python_cast (lambda s : s.split())
+  :alone all
 @@@
 
 @@@argtype table_vline |
@@ -94,6 +95,7 @@
 
   :pattern ((?^:outer^|inner^|all^|none)(?^:'index_subsets')?^|'indexed_range'^|\s+)+
   :python_cast (lambda s : s.split())
+  :alone all
 @@@
 
 @@@argtype table_span |
@@ -157,6 +159,7 @@
   calculated values.
   :pattern period^|comma
   :default period
+  :alone comma
 @@@
 
 @@@argtype table_justify |
diff --git a/tst/Makefile b/tst/Makefile
index b3fad84..2e12c6c 100644
--- a/tst/Makefile
+++ b/tst/Makefile
@@ -1,10 +1,12 @@
 # Klammertext distribution test suite (subset).
 #
-# Runs the six shell regression suites:
+# Runs the seven shell regression suites:
 #   cond_test.sh     — @cond argument delimitation
 #   deftype_test.sh  — the four klammer definition modes + redefinition table
 #   escape_test.sh   — target character escaping and quoted specials
 #   filename_test.sh — filenames with spaces (quoting, " / " lists, rescue)
+#   alone_test.sh    — an optional argument's three values (default, the
+#                      argument type's :alone value, a written value)
 #   modulepath_test.sh — @eval finds modules beside the file that names them
 #   editor_test.sh   — editor support (doc/edit): indentation and table
 #                      alignment; needs python3, uses Emacs when installed
@@ -17,5 +19,6 @@ test:
 	./deftype_test.sh
 	./escape_test.sh
 	./filename_test.sh
+	./alone_test.sh
 	./modulepath_test.sh
 	./editor_test.sh
diff --git a/tst/alone_test.sh b/tst/alone_test.sh
new file mode 100755
index 0000000..ed797b3
--- /dev/null
+++ b/tst/alone_test.sh
@@ -0,0 +1,240 @@
+#!/bin/bash
+#
+# alone_test.sh — Regression tests for an argument type's :alone value.
+#
+# An optional argument has three possible values, not two:
+#
+#   1. the option name is not written at all   -> the default
+#   2. the name is written alone, with no value -> the type's :alone value
+#   3. the name is written with a value         -> that value
+#
+# The :alone value is declared by the argument type (@@@argtype ... :alone),
+# never by a klammer's parameter declaration.  A default is what a klammer
+# means by silence and is properly per-klammer; a bare option name must read
+# the same way in every klammer, or a writer cannot know what it means
+# without consulting each signature.
+#
+# The bool type declares :alone true, which is where the convention that a
+# bare boolean option means true comes from.  This is a declaration like any
+# other type's, not an engine special case for booleans.
+#
+# A type whose pattern matches running text cannot declare an :alone value:
+# an option's value runs to the next bar or option name, so ":opt some words"
+# would take "some words" as the value and the alone value would never be
+# reached.  That is a definition-time error.
+#
+# Engine tier: these tests run with -k none and define their own argtypes
+# and klammers inline, so they do not depend on the Standard Klammer Set.
+#
+# Usage: ./alone_test.sh   (LSan suppressions come from env/runtime.env)
+# Exit code: 0 if all tests pass, 1 otherwise.
+
+PASS=0
+FAIL=0
+KTEXT=ktext
+K=${KLAMMERTEXT_HOME:?KLAMMERTEXT_HOME must be set}
+
+red=$'\033[31m'
+green=$'\033[32m'
+bold=$'\033[1m'
+reset=$'\033[0m'
+
+# strip leading/trailing blank lines and surrounding whitespace
+trim() { awk '{ sub(/[ \t\r]+$/, "") } { line[NR]=$0 } END { f=1; while (f<=NR && line[f]=="") f++; l=NR; while (l>=1 && line[l]=="") l--; for (i=f;i<=l;i++) print line[i] }'; }
+
+# check_eq TEST_NAME EXPECTED KTEXT_ARGS...
+#   Runs ktext, expects exit status 0, and compares trimmed stdout to EXPECTED.
+check_eq() {
+    local test_name="$1"
+    local expected="$2"
+    shift 2
+
+    local output status
+    output=$("$KTEXT" "$@" 2>/tmp/alone_test_err.$$)
+    status=$?
+    output=$(printf '%s' "$output" | trim)
+
+    if [ $status -ne 0 ]; then
+        echo "${red}FAIL${reset} $test_name — ktext exited $status"
+        echo "       stderr: $(head -3 /tmp/alone_test_err.$$)"
+        FAIL=$((FAIL + 1))
+        return
+    fi
+    if [ "$output" = "$expected" ]; then
+        echo "${green}PASS${reset} $test_name"
+        PASS=$((PASS + 1))
+    else
+        echo "${red}FAIL${reset} $test_name"
+        echo "       expected: [$expected]"
+        echo "       got:      [$output]"
+        FAIL=$((FAIL + 1))
+    fi
+}
+
+# check_error TEST_NAME PATTERN KTEXT_ARGS...
+#   Runs ktext, expects a NONZERO exit status and PATTERN in the message.
+check_error() {
+    local test_name="$1"
+    local pattern="$2"
+    shift 2
+
+    local output status
+    output=$("$KTEXT" "$@" 2>&1)
+    status=$?
+
+    if [ $status -eq 0 ]; then
+        echo "${red}FAIL${reset} $test_name — expected an error but ktext succeeded"
+        FAIL=$((FAIL + 1))
+        return
+    fi
+    if echo "$output" | grep -qF "$pattern"; then
+        echo "${green}PASS${reset} $test_name"
+        PASS=$((PASS + 1))
+    else
+        echo "${red}FAIL${reset} $test_name — expected error to contain [$pattern]"
+        echo "       output: $(echo "$output" | head -5)"
+        FAIL=$((FAIL + 1))
+    fi
+}
+
+# A type with both a default and an alone value, and a klammer using it.
+DEPTH='@@@argtype depth | a table of contents depth :pattern \d+ :default 0 :alone 3 @@@'
+DK='@@d :n.depth : [*n*] @@'
+
+# A type with an alone value but no default.
+MARK='@@@argtype mark | a mark character :pattern [-*+] :alone * @@@'
+MK='@@m :c.mark : [*c*] @@'
+
+echo "${bold}Argument type :alone value tests${reset}"
+echo "================================"
+echo
+
+# --- The three values of an optional argument ---
+
+check_eq \
+    " 1. name absent — the default" \
+    "[0]" \
+    -k none -s "$DEPTH $DK @d@" -d
+
+check_eq \
+    " 2. name written alone — the type's alone value" \
+    "[3]" \
+    -k none -s "$DEPTH $DK @d :n @" -d
+
+check_eq \
+    " 3. name written with a value — that value" \
+    "[7]" \
+    -k none -s "$DEPTH $DK @d :n 7 @" -d
+
+# --- A type with an alone value but no default ---
+
+check_eq \
+    " 4. no default declared — absent is empty" \
+    "[]" \
+    -k none -s "$MARK $MK @m@" -d
+
+check_eq \
+    " 5. no default declared — alone still applies" \
+    "[*]" \
+    -k none -s "$MARK $MK @m :c @" -d
+
+# --- The alone value belongs to the type, so every parameter of that
+#     type gets it, and a parameter default does not disturb it ---
+
+check_eq \
+    " 6. two parameters of one type share the alone value" \
+    "[3][3]" \
+    -k none -s "$DEPTH @@d2 :a.depth :b.depth : [*a*][*b*] @@ @d2 :a :b @" -d
+
+check_eq \
+    " 7. a parameter default overrides the type default, not the alone value" \
+    "[5]|[3]" \
+    -k none -s "$DEPTH @@d3 :n.depth 5 : [*n*] @@ @d3@|@d3 :n @" -d
+
+# --- bool: the convention that a bare boolean option means true ---
+
+check_eq \
+    " 8. bool written alone is true" \
+    "[true]" \
+    -k none -s '@@b :f.bool : [*f*] @@ @b :f @' -d
+
+check_eq \
+    " 9. bool written with false stays false" \
+    "[false]" \
+    -k none -s '@@b :f.bool : [*f*] @@ @b :f false @' -d
+
+check_eq \
+    "10. bool absent with no default is empty" \
+    "[]" \
+    -k none -s '@@b :f.bool : [*f*] @@ @b@' -d
+
+check_eq \
+    "11. bool absent with a true parameter default" \
+    "[true]" \
+    -k none -s '@@b :f.bool true : [*f*] @@ @b@' -d
+
+check_eq \
+    "12. bool false explicitly against a true default" \
+    "[false]" \
+    -k none -s '@@b :f.bool true : [*f*] @@ @b :f false @' -d
+
+# --- The value reaching @eval ---
+
+check_eq \
+    "13. python value of a bool written alone" \
+    "True" \
+    -k none -s '@@b :f.bool : @eval repr(K.f) @ @@ @b :f @' -d
+
+check_eq \
+    "14. python value of an absent bool" \
+    "None" \
+    -k none -s '@@b :f.bool : @eval repr(K.f) @ @@ @b@' -d
+
+check_eq \
+    "15. python value of a user type written alone" \
+    "'3'" \
+    -k none -s "$DEPTH @@d4 :n.depth : @eval repr(K.n) @ @@ @d4 :n @" -d
+
+# --- Types that cannot delimit a bare option name ---
+
+check_error \
+    "16. :alone refused on a type matching running text" \
+    "cannot declare an :alone value" \
+    -k none -s '@@@argtype loose | anything at all :alone x @@@' -d
+
+check_error \
+    "17. :alone refused on an explicit match-everything pattern" \
+    "cannot declare an :alone value" \
+    -k none -s '@@@argtype loose | anything :pattern (?:.^|\n)* :alone x @@@' -d
+
+check_error \
+    "18. an alone value must match its own type's pattern" \
+    "does not match its own pattern" \
+    -k none -s '@@@argtype depth | a depth :pattern \d+ :alone many @@@' -d
+
+# --- Delimitation: an option value still runs to the next bar or option
+#     name, so text after a bare name is taken as the value and rejected
+#     by the type.  This is what makes the guard above necessary.
+
+check_error \
+    "19. text after a bare option name is taken as its value" \
+    "does not match" \
+    -k none -s "$DEPTH $DK @d :n some words @" -d
+
+check_eq \
+    "20. a bar separates a bare option name from following text" \
+    "[3]two" \
+    -k none -s "$DEPTH @@d5 :n.depth | t : [*n*]*t* @@ @d5 :n | two @" -d
+
+# --- A type with no alone value is unchanged: a bare name is empty ---
+
+check_eq \
+    "21. bare option of a type with no alone value is empty" \
+    "[]" \
+    -k none -s '@@s :t.word : [*t*] @@ @s :t @' -d
+
+echo
+echo "================================"
+echo "Passed: $PASS  Failed: $FAIL"
+rm -f /tmp/alone_test_err.$$
+[ $FAIL -eq 0 ]