diff --git a/README.md b/README.md
index e540c19..e2f348c 100644
--- a/README.md
+++ b/README.md
@@ -3209,23 +3209,23 @@ c  6  7
 | l.join(r, lsuffix='l', |    x yl yr  z |            | x yl yr  z | Joins/merges on row keys.|
 |           rsuffix='r', | a  1  2  .  . | x yl yr  z | 1  2  .  . | Uses 'left' by default.  |
 |           how=…)       | b  3  4  4  5 | 3  4  4  5 | 3  4  4  5 | If r is a series, it is  |
-|                        | c  .  .  6  7 |            |            | first converted to DF.   |
+|                        | c  .  .  6  7 |            |            | treated as a column.     |
 +------------------------+---------------+------------+------------+--------------------------+
 | pd.concat([l, r],      |    x   y   z  |     y      |            | Adds rows at the bottom. |
 |           axis=0,      | a  1   2   .  |     2      |            | Uses 'outer' by default. |
-|           join=…)      | b  3   4   .  |     4      |            | By default works the     |
-|                        | b  .   4   5  |     4      |            | same as `l.append(r)`.   |
-|                        | c  .   6   7  |     6      |            |                          |
+|           join=…)      | b  3   4   .  |     4      |            | A series is treated as a |
+|                        | b  .   4   5  |     4      |            | column. Use l.append(r)  |
+|                        | c  .   6   7  |     6      |            | to add a row instead.    |
 +------------------------+---------------+------------+------------+--------------------------+
 | pd.concat([l, r],      |    x  y  y  z |            |            | Adds columns at the      |
-|           axis=1,      | a  1  2  .  . | x  y  y  z |            | right end.               |
-|           join=…)      | b  3  4  4  5 | 3  4  4  5 |            | Uses 'outer' by default. |
-|                        | c  .  .  6  7 |            |            |                          |
+|           axis=1,      | a  1  2  .  . | x  y  y  z |            | right end. Uses 'outer'  |
+|           join=…)      | b  3  4  4  5 | 3  4  4  5 |            | by default. A series is  |
+|                        | c  .  .  6  7 |            |            | treated as a column.     |
 +------------------------+---------------+------------+------------+--------------------------+
 | l.combine_first(r)     |    x   y   z  |            |            | Adds missing rows and    |
-|                        | a  1   2   .  |            |            | columns.                 |
-|                        | b  3   4   5  |            |            |                          |
-|                        | c  .   6   7  |            |            |                          |
+|                        | a  1   2   .  |            |            | columns. Also updates    |
+|                        | b  3   4   5  |            |            | cells that contain NaN.  |
+|                        | c  .   6   7  |            |            | R must be a DataFrame.   |
 +------------------------+---------------+------------+------------+--------------------------+
 ```
 
diff --git a/index.html b/index.html
index 0252554..1cf9f92 100644
--- a/index.html
+++ b/index.html
@@ -2746,23 +2746,23 @@ c  <span class="hljs-number">6</span>  <span class="hljs-number">7</span>
 ┃ l.join(r, lsuffix=<span class="hljs-string">'l'</span>, │    x yl yr  z │            │ x yl yr  z │ Joins/merges on row keys.┃
 ┃           rsuffix=<span class="hljs-string">'r'</span>, │ a  <span class="hljs-number">1</span>  <span class="hljs-number">2</span>  .  . │ x yl yr  z │ <span class="hljs-number">1</span>  <span class="hljs-number">2</span>  .  . │ Uses <span class="hljs-string">'left'</span> by default.  ┃
 ┃           how=…)       │ b  <span class="hljs-number">3</span>  <span class="hljs-number">4</span>  <span class="hljs-number">4</span>  <span class="hljs-number">5</span> │ <span class="hljs-number">3</span>  <span class="hljs-number">4</span>  <span class="hljs-number">4</span>  <span class="hljs-number">5</span> │ <span class="hljs-number">3</span>  <span class="hljs-number">4</span>  <span class="hljs-number">4</span>  <span class="hljs-number">5</span> │ If r is a series, it is  ┃
-┃                        │ c  .  .  <span class="hljs-number">6</span>  <span class="hljs-number">7</span> │            │            │ first converted to DF.   ┃
+┃                        │ c  .  .  <span class="hljs-number">6</span>  <span class="hljs-number">7</span> │            │            │ treated as a column.     ┃
 ┠────────────────────────┼───────────────┼────────────┼────────────┼──────────────────────────┨
 ┃ pd.concat([l, r],      │    x   y   z  │     y      │            │ Adds rows at the bottom. ┃
 ┃           axis=<span class="hljs-number">0</span>,      │ a  <span class="hljs-number">1</span>   <span class="hljs-number">2</span>   .  │     <span class="hljs-number">2</span>      │            │ Uses <span class="hljs-string">'outer'</span> by default. ┃
-┃           join=…)      │ b  <span class="hljs-number">3</span>   <span class="hljs-number">4</span>   .  │     <span class="hljs-number">4</span>      │            │ By default works the     ┃
-┃                        │ b  .   <span class="hljs-number">4</span>   <span class="hljs-number">5</span>  │     <span class="hljs-number">4</span>      │            │ same as `l.append(r)`.   ┃
-┃                        │ c  .   <span class="hljs-number">6</span>   <span class="hljs-number">7</span>  │     <span class="hljs-number">6</span>      │            │                          ┃
+┃           join=…)      │ b  <span class="hljs-number">3</span>   <span class="hljs-number">4</span>   .  │     <span class="hljs-number">4</span>      │            │ A series is treated as a ┃
+┃                        │ b  .   <span class="hljs-number">4</span>   <span class="hljs-number">5</span>  │     <span class="hljs-number">4</span>      │            │ column. Use l.append(r)  ┃
+┃                        │ c  .   <span class="hljs-number">6</span>   <span class="hljs-number">7</span>  │     <span class="hljs-number">6</span>      │            │ to add a row instead.    ┃
 ┠────────────────────────┼───────────────┼────────────┼────────────┼──────────────────────────┨
 ┃ pd.concat([l, r],      │    x  y  y  z │            │            │ Adds columns at the      ┃
-┃           axis=<span class="hljs-number">1</span>,      │ a  <span class="hljs-number">1</span>  <span class="hljs-number">2</span>  .  . │ x  y  y  z │            │ right end.               ┃
-┃           join=…)      │ b  <span class="hljs-number">3</span>  <span class="hljs-number">4</span>  <span class="hljs-number">4</span>  <span class="hljs-number">5</span> │ <span class="hljs-number">3</span>  <span class="hljs-number">4</span>  <span class="hljs-number">4</span>  <span class="hljs-number">5</span> │            │ Uses <span class="hljs-string">'outer'</span> by default. ┃
-┃                        │ c  .  .  <span class="hljs-number">6</span>  <span class="hljs-number">7</span> │            │            │                          ┃
+┃           axis=<span class="hljs-number">1</span>,      │ a  <span class="hljs-number">1</span>  <span class="hljs-number">2</span>  .  . │ x  y  y  z │            │ right end. Uses <span class="hljs-string">'outer'</span>  ┃
+┃           join=…)      │ b  <span class="hljs-number">3</span>  <span class="hljs-number">4</span>  <span class="hljs-number">4</span>  <span class="hljs-number">5</span> │ <span class="hljs-number">3</span>  <span class="hljs-number">4</span>  <span class="hljs-number">4</span>  <span class="hljs-number">5</span> │            │ by default. A series is  ┃
+┃                        │ c  .  .  <span class="hljs-number">6</span>  <span class="hljs-number">7</span> │            │            │ treated as a column.     ┃
 ┠────────────────────────┼───────────────┼────────────┼────────────┼──────────────────────────┨
 ┃ l.combine_first(r)     │    x   y   z  │            │            │ Adds missing rows and    ┃
-┃                        │ a  <span class="hljs-number">1</span>   <span class="hljs-number">2</span>   .  │            │            │ columns.                 ┃
-┃                        │ b  <span class="hljs-number">3</span>   <span class="hljs-number">4</span>   <span class="hljs-number">5</span>  │            │            │                          ┃
-┃                        │ c  .   <span class="hljs-number">6</span>   <span class="hljs-number">7</span>  │            │            │                          ┃
+┃                        │ a  <span class="hljs-number">1</span>   <span class="hljs-number">2</span>   .  │            │            │ columns. Also updates    ┃
+┃                        │ b  <span class="hljs-number">3</span>   <span class="hljs-number">4</span>   <span class="hljs-number">5</span>  │            │            │ cells that contain NaN.  ┃
+┃                        │ c  .   <span class="hljs-number">6</span>   <span class="hljs-number">7</span>  │            │            │ R must be a DataFrame.   ┃
 ┗━━━━━━━━━━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━┷━━━━━━━━━━━━┷━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━┛
 </code></pre>
 <div><h4 id="aggregatetransformmap-1">Aggregate, Transform, Map:</h4><pre><code class="python language-python hljs">&lt;Sr&gt; = &lt;DF&gt;.sum/max/mean/idxmax/all()         <span class="hljs-comment"># Or: &lt;DF&gt;.apply/agg/transform(&lt;agg_func&gt;)</span>
diff --git a/parse.js b/parse.js
index 458c3ec..e1acf8c 100755
--- a/parse.js
+++ b/parse.js
@@ -347,23 +347,23 @@ const DIAGRAM_15_B =
   "┃ l.join(r, lsuffix='l', │    x yl yr  z │            │ x yl yr  z │ Joins/merges on row keys.┃\n" +
   "┃           rsuffix='r', │ a  1  2  .  . │ x yl yr  z │ 1  2  .  . │ Uses 'left' by default.  ┃\n" +
   "┃           how=…)       │ b  3  4  4  5 │ 3  4  4  5 │ 3  4  4  5 │ If r is a series, it is  ┃\n" +
-  "┃                        │ c  .  .  6  7 │            │            │ first converted to DF.   ┃\n" +
+  "┃                        │ c  .  .  6  7 │            │            │ treated as a column.     ┃\n" +
   "┠────────────────────────┼───────────────┼────────────┼────────────┼──────────────────────────┨\n" +
   "┃ pd.concat([l, r],      │    x   y   z  │     y      │            │ Adds rows at the bottom. ┃\n" +
   "┃           axis=0,      │ a  1   2   .  │     2      │            │ Uses 'outer' by default. ┃\n" +
-  "┃           join=…)      │ b  3   4   .  │     4      │            │ By default works the     ┃\n" +
-  "┃                        │ b  .   4   5  │     4      │            │ same as `l.append(r)`.   ┃\n" +
-  "┃                        │ c  .   6   7  │     6      │            │                          ┃\n" +
+  "┃           join=…)      │ b  3   4   .  │     4      │            │ A series is treated as a ┃\n" +
+  "┃                        │ b  .   4   5  │     4      │            │ column. Use l.append(r)  ┃\n" +
+  "┃                        │ c  .   6   7  │     6      │            │ to add a row instead.    ┃\n" +
   "┠────────────────────────┼───────────────┼────────────┼────────────┼──────────────────────────┨\n" +
   "┃ pd.concat([l, r],      │    x  y  y  z │            │            │ Adds columns at the      ┃\n" +
-  "┃           axis=1,      │ a  1  2  .  . │ x  y  y  z │            │ right end.               ┃\n" +
-  "┃           join=…)      │ b  3  4  4  5 │ 3  4  4  5 │            │ Uses 'outer' by default. ┃\n" +
-  "┃                        │ c  .  .  6  7 │            │            │                          ┃\n" +
+  "┃           axis=1,      │ a  1  2  .  . │ x  y  y  z │            │ right end. Uses 'outer'  ┃\n" +
+  "┃           join=…)      │ b  3  4  4  5 │ 3  4  4  5 │            │ by default. A series is  ┃\n" +
+  "┃                        │ c  .  .  6  7 │            │            │ treated as a column.     ┃\n" +
   "┠────────────────────────┼───────────────┼────────────┼────────────┼──────────────────────────┨\n" +
   "┃ l.combine_first(r)     │    x   y   z  │            │            │ Adds missing rows and    ┃\n" +
-  "┃                        │ a  1   2   .  │            │            │ columns.                 ┃\n" +
-  "┃                        │ b  3   4   5  │            │            │                          ┃\n" +
-  "┃                        │ c  .   6   7  │            │            │                          ┃\n" +
+  "┃                        │ a  1   2   .  │            │            │ columns. Also updates    ┃\n" +
+  "┃                        │ b  3   4   5  │            │            │ cells that contain NaN.  ┃\n" +
+  "┃                        │ c  .   6   7  │            │            │ R must be a DataFrame.   ┃\n" +
   "┗━━━━━━━━━━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━┷━━━━━━━━━━━━┷━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━┛\n";
 
 const DIAGRAM_16_A =