diff --git a/test/spec.txt b/test/spec.txt
@@ -5964,18 +5964,22 @@ The following rules define emphasis and strong emphasis:
9. Emphasis begins with a delimiter that [can open emphasis] and ends
with a delimiter that [can close emphasis], and that uses the same
- character (`_` or `*`) as the opening delimiter. There must
- be a nonempty sequence of inlines between the open delimiter
- and the closing delimiter; these form the contents of the emphasis
- inline.
+ character (`_` or `*`) as the opening delimiter. The
+ opening and closing delimiters must belong to separate
+ [delimiter runs]. If one of the delimiters can both
+ open and close emphasis, then the sum of the lengths of the
+ delimiter runs containing the opening and closing delimiters
+ must not be a multiple of 3.
10. Strong emphasis begins with a delimiter that
[can open strong emphasis] and ends with a delimiter that
[can close strong emphasis], and that uses the same character
- (`_` or `*`) as the opening delimiter.
- There must be a nonempty sequence of inlines between the open
- delimiter and the closing delimiter; these form the contents of
- the strong emphasis inline.
+ (`_` or `*`) as the opening delimiter. The
+ opening and closing delimiters must belong to separate
+ [delimiter runs]. If one of the delimiters can both open
+ and close strong emphasis, then the sum of the lengths of
+ the delimiter runs containing the opening and closing
+ delimiters must not be a multiple of 3.
11. A literal `*` character cannot occur at the beginning or end of
`*`-delimited emphasis or `**`-delimited strong emphasis, unless it
@@ -5999,9 +6003,7 @@ the following principles resolve ambiguity:
so that the second begins before the first ends and ends after
the first ends, the first takes precedence. Thus, for example,
`*foo _bar* baz_` is parsed as `<em>foo _bar</em> baz_` rather
- than `*foo <em>bar* baz</em>`. For the same reason,
- `**foo*bar**` is parsed as `<em><em>foo</em>bar</em>*`
- rather than `<strong>foo*bar</strong>`.
+ than `*foo <em>bar* baz</em>`.
16. When there are two potential emphasis or strong emphasis spans
with the same closing delimiter, the shorter one (the one that
@@ -6581,18 +6583,30 @@ __foo_ bar_
<p><em>foo <strong>bar</strong> baz</em></p>
````````````````````````````````
-
-But note:
-
```````````````````````````````` example
*foo**bar**baz*
.
-<p><em>foo</em><em>bar</em><em>baz</em></p>
+<p><em>foo<strong>bar</strong>baz</em></p>
````````````````````````````````
+Note that in the preceding case, the interpretation
+
+``` markdown
+<p><em>foo</em><em>bar<em></em>baz</em></p>
+```
+
+
+is precluded by the condition that a delimiter that
+can both open and close (like the `*` after `foo`
+cannot form emphasis if the sum of the lengths of
+the delimiter runs containing the opening and
+closing delimiters is a multiple of 3.
+
+The same condition ensures that the following
+cases are all strong emphasis nested inside
+emphasis, even when the interior spaces are
+omitted:
-The difference is that in the preceding case, the internal delimiters
-[can close emphasis], while in the cases with spaces, they cannot.
```````````````````````````````` example
***foo** bar*
@@ -6608,17 +6622,18 @@ The difference is that in the preceding case, the internal delimiters
````````````````````````````````
-Note, however, that in the following case we get no strong
-emphasis, because the opening delimiter is closed by the first
-`*` before `bar`:
-
```````````````````````````````` example
*foo**bar***
.
-<p><em>foo</em><em>bar</em>**</p>
+<p><em>foo<strong>bar</strong></em></p>
````````````````````````````````
+```````````````````````````````` example
+*foo**bar***
+.
+<p><em>foo<strong>bar</strong></em></p>
+````````````````````````````````
Indefinite levels of nesting are possible:
@@ -6712,18 +6727,13 @@ ____foo__ bar__
````````````````````````````````
-But note:
-
```````````````````````````````` example
**foo*bar*baz**
.
-<p><em><em>foo</em>bar</em>baz**</p>
+<p><strong>foo<em>bar</em>baz</strong></p>
````````````````````````````````
-The difference is that in the preceding case, the internal delimiters
-[can close emphasis], while in the cases with spaces, they cannot.
-
```````````````````````````````` example
***foo* bar**
.
@@ -7039,13 +7049,6 @@ Rule 15:
```````````````````````````````` example
-**foo*bar**
-.
-<p><em><em>foo</em>bar</em>*</p>
-````````````````````````````````
-
-
-```````````````````````````````` example
*foo __bar *baz bim__ bam*
.
<p><em>foo <strong>bar *baz bim</strong> bam</em></p>